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NASA-CP-2213 19820013380 NASA Conference Publication 2213 



Space Power 
Subsystem 
Automation 
Technology 



LAI- 



Proceedings of a workshop held at 

Marshall Space Flight Center, Alabama 

October 28-29, 1981 



IVASA 



NASA Conference Publication 2213 

Space Power 
Subsystem 
Automation 
Technology 



James R. Graves, Compiler 
George C. Marshall Space Flight Center 
Marshall Space Flight Center, Alabama 

Proceedings of a workshop held at 

Marshall Space Flight Center, Alabama 

October 28-29, 1981 



(W\SA 

National Aeronautics 
and Space Administration 



Scientific and Technical 
Information Branch 

1982 



CONTENTS 

Page 
FOREWORD i1i 

CONFERENCE AGENDA 1 

WORKSHOP ASSIGNMENTS 3 



IMPROVE SPACECRAFT AFFORDABI LITY THROUGH AUTOMATION 5 

Richard F. Carlisle 



WORKSHOP PURPOSE 9 

J. P. Mull in 



POWER SYSTEM COMPONENT MODELING PROGRAM 15 

Lou SI i fer 



RECENT ADVANCES IN-AUTOMATION COMPONENTS TECHNOLOGY 35 

Bob Finke 



AUTOMATION TECHNOLOGY FOR POWER SYSTEM MANAGEMENT 57 

Ron Larson 



SPACECRAFT SYSTEM/POWER SUBSYSTEM INTERACTIONS 69 

Chris Carl 



TECHNICIAL ISSUES IN POWER SYSTEM AUTONOMY FOR 

PLANETARY SPACECRAFT 87 

Fred C. Vote 



MARTIN MARIETTA POWER SYSTEM AUTOMATION EXPERIENCE 119 

Fred Lukens 



111 



Page 

AIR FORCE REQUIREMENTS FOR POWER SYSTEM AUTOMATION 137 

Dave Massie 



POWER SYSTEM AUTOMATION REQUIREMENTS FOR EARTH ORBIT 155 

J. R. Lanier, Jr. 



AMPS PROGRAM STATUS AND OBJECTIVES 163 

Arthur D. Schoenfeld 



"STRAWMAN" TECHNOLOGY ISSUES AND SPECIFIC OBJECTIVES 177 

Jim Graves 



REPORT OF WORKSHOP GROUP NO. 1 189 

Sidney W. Silverman 



REPORT OF WORKSHOP GROUP NO. 2 193 

Floyd E. Ford 



REPORT OF WORKSHOP GROUP NO. 3 199 

Howard We iner 



REPORT OF WORKSHOP GROUP NO. 4 205 

Wayne Wagnon 



ATTENDANCE LIST 211 



IV 



SPACE POWER SYSTEM AUTOMATION WORKSHOP 

MARSHALL SPACE FLIGHT CENTER 

OCTOBER 28 - 29, 1981 

BLDG 4610 ROOM 5025 

AGENDA 

WEDNESDAY/ OCTOBER 28 

8:30-8:45 - INTRODUCTION JIM MILLER 

8:45-9:00 - OPENING REMARKS DICK CARLISLE 

9 : 00 - 9 : 15 - POWER SYSTEM AUTOMATION PLANS . . JERRY MULLIN 

9:15-9:45 - P0V7ER SYSTEM COMPONENT 

MODELING PROGRAM LOU SLIFER 

9:45-10:15 - RECENT ADVANCES IN AUTOMATION 

COMPONENTS TECHNOLOGY BOB FINKE 

10:15-10:45 - AUTOMATION TECHNOLOGY FOR 

POl'ffiR SYSTEM MANAGEMENT .... RON LARSON 

10:45-11:15 - SPACECRAFT SYSTEM/POWER SUB- 
SYSTEM INTERACTIONS CHRIS CARL 

11:15 - 11:45 - TECHNICAL ISSUES IN POWER SYSTEM 

~ AUTONOMY FOR PLANETARY SPACE- 
CRAFT FRED VOTE 

11:45 - 12 : 15 - POWER SYSTEM AUTOMATION 

EXPERIENCE AT MARTIN FRED LUKENS 

12:15-1:15 - LUNCH 

1:15-1:45 - AIR FORCE REQUIREMENTS FOR 

POWER SYSTEM AUTOMATION .... DAVE 14ASSIE 

1 : 45 - 2 : 15 - POVJER SYSTEM AUTOMATION 

REQUIREMENTS FOR EARTH ORBIT. . ROY LANIER 

2:15-3:00 - AMPS PROGRAM STATUS 

AND OBJECTIVES ART SCHOENFELD 

3:00-3:30 - STRAWI4AN IDENTIFICATION OF 

TECHNOLOGY ISSUES AND SPECIFIC 

AUTOMATION OBJECTIVES JIM GRAVES 

3:30-4:00 - GROUP DISCUSSION JIM MILLER 

5:30-7:00 - DINNER AT THE ELEGANT STEAK ROOM 



THURSDAY/OCTOBER 29 ( ROOMS AS INDICATED) 



8:00 - 12:00 - WORKSHOP DISCUSSIONS 



12:00 - 1:00 



o TECHNOLOGY ISSUES IDENTIFICATION 
GROUP 1 (Bldg. 4487 - Rm. A-204) 
GROUP 2 (Bldg. 4487 - Rm. A-214) 

o SPECIFIC AUTOMATION OBJECTIVES 
GROUP 3 (Bldg, 4610 - Rm. 5025) 
GROUP 4 (Bldg. 4487 - Rm. 238) 

LUNCH 



WORKSHOP CHAIRMAN 



SID SILVERMAN 



FLOYD FORD 



HOWARD WEINER 
WAYNE WAGNON 



BLDG. 4610 - ROOM 5025: 



1:00 - 2:30 



TECHNOLOGY ISSUES REPORT 



WORKSHOP CHAIRMAN 



2:30 - 4:00 - SPECIFIC OBJECTIVES REPORT WORKSHOP CHAIRMAN 

4:00 - WRAP UP AND TURN IN WORKSHOP RESULTS JIM MILLER 



WORKSHOP ASSIGlNlMENTS 



TECHNOLOGY ISSUES 

GROUP 1 
BLDG. 4487. ROOM A- 204 

SID SILVERMAN/ CHAIRMAN 

DICK CARLISLE 

MATT IMI4AMURA 

BILL BRANNIAN 

DAVE PETERSON 

BOB GIUDICI 

ROY LANIER 

JOHN ARMANTROUT 

DOUG TURNER 



GROUP 2 
BLDG. 4487, ROOM A-214 

FLOYD FORD/ CHAIRMAN 

FRED VOTE 

JOHN LEAR 

CHARLIE SOLLO 

JOE NAVARRO 

MIKE GLASS 

DON ROUTH 

WAYNE HUDSON 

DON WILLIAMS 



SPECIFIC OBJECTIVES 

GROUP 3 
BLDG. 4610. ROOM 5025 

HOWARD WE INER/ CHAIRMAN 

JERRY MULLIN 

CHRIS CARL 

JIM WILLIAl^S 

KENT DECKER 

GEORGE VON TIESENHAUSEN 

JACK MACPHERSON 

JOE VOSS 

LU SLIFER 

LT. ED GJEPJ^NDSEN 



GROUP 4 
BLDG. 4487. ROOM B-238 

WAYNE WAGNON/CKAIRl'lAN 

RON LARSON 

FP^D LUKENS 

ART SCHOENFELD 

RON GIVEN 

IRVING STEIN 

C. S. CROWELL 

DAVE MASS IE 

DICK GUALDONI 



IMPROVE SPACECRAFT AFFORDABILITY 
THROUGH AUTOMATION 

BY 

RICHARD F. CARLISLE 

MANAGER, SPACECRAFT SYSTEMS OFFICE 

OAST 



Introduction 



The goal of the spacecraft Technology Automation task is to reduce 
the spacecraft life cycle cost, extend expected spacecraft opera- 
tional life, and improve performance. 

Life cycle cost includes the cost of non-recurring design, manu- 
facturing and test, launch, and on-orbit operation including 
maintenance, repair, and redundance management. The operation 
cost to meet ten year satisfactory performance adds considerable 
spacecraft complexity with respect to redundancy management and 
fault tolerant design. Spacecraft self management by automation 
can offer considerable operation costs benefits. The more complex 
the spacecraft, the larger the benefit of automation whether 
implemented on board the spacecraft or on the ground. 

The technology development schedule has a severe sense of urgency 
based on current NASA planning that requires a technology readi- 
ness for a potential FY 1986 phase C/D major new start for an Earth 
orbiting vehicle that will establish a long term United States 
prominance in space. 

Spacecraft Automation Technology Approach 

The approach planned by OAST is to establish a long term automation 
objective with phased technology outputs ^ The long term objective 
includes a high degree of automation that will require minimum 
involvement of man. A short term, low risk, objective is to 
automate the present manned involvement thus reducing the routine 
ground operational support. This can be a major early cost savings 
even if the initial application is automated on the ground. The 
decision to transfer these functions to the spacecraft will 
probably be made based on economics and/or the availability of 
hardware. 

The planned OAST FY 1982 Spacecraft Automation Technology task is 
comprised of three major tasks. JPL will study a total spacecraft 
performance requirement and prepare an automation technology plan 
at the spacecraft level. This plan will be based on a review of 
the baseline automation of the existing Voyager spacecraft. It 
will expand to a strawman generic future spacecraft automation 
design. The task will trade-off such things' as: ^ central vs 
distributed control, alternative spacecraft automation architec- 
ture, heirarchial command and control ground rules, interfaces 
between spacecraft subsystems and mission rules to establish 
priorities when conflicts occur in the spacecraft command and 
control system. 



If there were sufficient funds available, it would be desirable 
to conduct subsystem automation technology tasks in each of the 
spacecraft systems as part of the spacecraft automation task. 
With limited funds, we plan to initially develop the automation 
design for only the power subsystem in parallel with the broad- 
spacecraft task. Task 2, the power system automation task will 
be performed by MSFC. The details of Tasks 1 & 2 are somewhat a 
function of the output of this workshop. Task 3 will be the 
development of generic automation technologies. 

It is highly desirable that the power system automation task 
achieve both a long term objective and a near term benefit. It 
is envisioned that this can be successfully accomplished from an 
orderly and systematic growth of a power system automation tech- 
nology development program that is compatible with a parallel 
spacecraft system automation program. Other systems, in turn, can 
benefit from the efforts in the power system automation task. 

The degree of power system automation can increase with time. 
There is little urgency to eliminate manned involvement com- 
pletely. The DoD has an autonomy requirement with respect to 
security and/or survivability. The degree of autonomy (operation 
with no involvement of man) required with respect to time in- 
creases the complexity and cost of the orbiting spacecraft in a 
non-linear way. Therefore, the af fordability benefit of auto- 
mation is significantly impacted by the degree of autonomy. The 
technology to enable, and the cost-benefits of automation, will 
be determined by future trade-off studies. 

I expect that the spacecraft and power systems automation tasks 
will continue for several years. The two tasks must establish a 
technology interface between them. Orderly periodic interactions 
must occur between the two tasks. This interaction will result 
in the definition of interfaces between the two programs and these 
interfaces will in some cases become design constraints on either 
or both programs. These constraints must be reviewed and modified 
in the best interest of the spacecraft systems in order that this 
coordinated program can provide the technology to support an 
optimized spacecraft design. 

Later this morning you will hear a presentation by Chris Carl that 
will describe JPL's background and experience in spacecraft 
automation. He will also discuss the current spacecraft auto- 
mation approach and will establish the initial spacecraft/power 
system automation interaction. I expect the spacecraft system 
automation task will eventually involve a spacecraft system 
simulation. I also expect the power system automation technology 
output will result in a power system automation simulation that 
can be integrated into the spacecraft system simulation and can 
be implemented in a MSFC power system breadboard. 



you will hear also this morning from Ron Larsen, who will discuss 
generic automation technology. He will describe degrees of 
automation from simple preprogramming to the orderly sequencing 
of man's logic process that will enable the capturing' of the 
complex methodology of decision making involving interactive non- 
linear functions. He will discuss the technique of capturing the 
experience of experts and the mathematics and methodology of 
interrelating this experience into the control of complex mecha- 
nisms. He will introduce you to the generic technology of 
automation software development. The initial generic automation 
task is planned to be^ focused on the experience of a "battery 
systems engineer" as applicable to the on-orbit management of a 
battery system. 

In summary, the Spacecraft Systems Automation Technology tasks 
consist of three parallel tasks; spacecraft automation to estab- 
lish the total spacecraft philosophy; power system automation 
techniques compatible with the system philosophy and near term 
benefits; and, generic automation technology to develop auto- 
mation methodology and automation software design. 

I am pleased to see the interest illustrated by the collective 
experience I know you represent. I want to assure you that your 
recommendations will be seriously evaluated and considered. I am 
certain in the next two days you are going to make a significant 
impact on our program. I am pleased to be here with you and am 
anxious to see how you will advise us. 



WORKSHOP PURPOSE 



o IDENTIFY TECHNOLOGY ISSUES RELATIVE TO SPACE 
POWER SYSTEM AUTOMATION DEVELOPMENT 

o ESTABLISH SPECIFIC AUTOMATION OBJECTIVES RELATIVE 
TO SPACE POWER SYSTEM AUTOMATION DEVELOPMENT 



J. P. Mullin 



MSFC AUTOMATION MEETING 



10/28/81 



MAJOR NASA THRUSTS 



NOW - GET SHUTTLE OPERATIONAL 



o 



NEXT - ESTABLISH 'PERMANENT' MANNED LEO PRESENCE 



OAST THRUST 

WORK TECHNOLOGY 

TOWARD START IN 

85 86 87 



J. P. Mullin 



10/28/81 



MSFC AUTOl^TION MEETING 



o 



SPACE POWER THRUSTS 

FOR THE PAST FIVE YEARS PROGRAl^l DIRECTED TOWAPJ) CRITICAL 
TECHNOLOGIES NEEDED FOR HIGH POT-JER IN LEO/A MAJOR SPACE 
STATION REQUIREMENT 

- HIGH POVJER LOW COSt SOLAR ARRAYS-LARGE CELLS, CONCENTRATORS 
HIGH CAPACITY LONG LIFE ENERGY STORAGE - FUEL CELL - 
ELECTROLYSIS, NiH2 BATTERY 

- HIGH POVffiR COMPONENTS - TRANSISTORS, CAPACITORS, TRANSFOR^ffiRS , 
SWITCHES 

UNDERSTANDING OF PLASm INTERACTIONS - PIX I & II, NASCAP 
THERMAL COI^PONENTS - HEAT PIPES, RADIATORS 
ENERGY llANAGEMENT 



THE BIGGEST DEFICIENCY IN PRESENT 
PROGRAM IS IN THERMAL AND ELECTRI- 
.CAL ENERGY MANAGEMENT 



J. P. Mullin 



ro 



10/28/81 

OAST ENERGY MANAGEMENT BACKGROUND 

o APSM PROGRAM (AUTOMATED POVJER SYSTEM MGT) 
o 1975 - 1981/$2M 

o COMPARED AUTOMATED BASELINE VERSION OF PLANETARY S/C (V075) POWER 
SYSTEM - NO THERMAL 

o AUTOMATED VERSION PROVIDED 

50% < OPERATIONS COST 

50% > SPECIFIC POWER 

A - 40% < CAPITAL COST 

IMPROVED FAULT TOLERANCE /FLEXIBILITY 

o LAPS FLIGHT PROGRAM - REQUIRED ON BOARD AUTOMATION OF ION THRUSTER ENGINEER 

o AMPS PROGRAM 

o IN PROCESS NOW 

o ESTABLISH UTILITY - LIKE CAPABILITY TO MANAGE HIGH CAPACITY LEO ENERGY 
SYSTEM - ELECTRICAL & THERMAL/ARBITRARY 250 kW REFERENCE SYSTEM 

o l^IAJOR OAST - WIDE AUTOMATION THRUST ADOPTED - FYS 2 

o AMPS UNDER REVIEW FOR COORDINATION WITH OVERALL OAST THRUST 



J. P. Mullin 



10/28/81 



PURPOSE 
o IDENTIFY TECHNOLOGY ISSUES IN LEO ENERGY MANAGEMENT 
o RANK CRITICAL TECHNOLOGY NEEDS -BARRIERS 
o RECOMMEND TECHNOLOGY OBJECTIVES 
O COMMENT ON STRAWMAN 
o INVOLVE AUTOMATION AS WELL AS POWER TECHNOLOGISTS 




J. P. Mullin 



POWER SYSTEM COMPONENT MODELING PROGRAM 
( MODEL I NG/AUTOMAT I ON/AUTONOMY ) 

PRESENTATION TO: 
SPACE POVER SYSTEM AUTOMATION WORKSHOP 



L. SLIFER 
10/28/81 



ANALYTICAL MODELING 

recommendation: 

1, develop ac models for power subsystem components 

2, synthesize analytical model for power system 

3, define necessary parameters for electronic 
simulation of ac solar array model 

rationale: 

very little ac data available for components and system 

existing data needs review^ revision^ refinement and 
updating 

guidelines needed for accurate electronic simulation 

electronic array simulation is needed - only known way to 
include large arrays in ground tests 

PAYOFF: 

SAFEGUARD AGAINST BUS INSTABILITY 

AVOID HARMFUL INTERACTION BETWEEN ARRAY AND FILTER COMPONENTS 
AT OUTPUT 

DEFINE SOURCE IMPEDANCE AT LOAD BUS 

SUPPLEMENT INADEQUATE DC ARRAY SIMULATORS WITH MORE ACCURATE 
AND REALISTIC AC SIMULATION 



STATE OF HEALTH MONITORING 



recommendation: 

1. develop improved techniques for on-board monitoring and 
control of power system and its components 

software/hardware techniques to minimize 

impact on data handling and command system 

ground operations 
identify required state of health diagnostic measurements 
develop sensing techniques and sensors for detecting 

partial failures 

degradation 

2. define techniques for reducing complexity of managing degraded 
system/components from ground 

rationale; 

EXISTING ON-BOARD SENSORS/mEASUREMENTS INADEQUATE FOR ACCURATE 

DEFINITION OF STATE OF HEALTH 

GROUND MONITORING AND ANALYSIS IS INADEQUATE AND EXPENSIVE 

GROUND CONTROL IS COMPLEX AND SLOW TO RESPOND 

INADEQUACIES AFFECT MISSION PLANNING AND FLIGHT OPERATIONS 

REAL EFFECTS OF ENVIRONMENT ON SYSTEM ARE NOT KNOWN 

PAYOFF ! 

LOWER GROUND SUPPORT COST 

IMPROVED RESPONSE IN COMPENSATING FOR PARTIAL FAILURE/DEGRADATION 

IMPROVED DESIGN CAPABILITY 

IMPROVED MISSION OPERATIONS 

LOWER POWER SYSTEM COST AND WEIGHT 

SIMPLIFICATION IN C & DH SYSTEM 



00 



SPACE SYSTEfl 



PRE-LAUNCH 
AND LAUNCH 
OPERATIONS 



OPERATIONS 
CENTER 




CONTROL 
CENTER 



SPACE 
SEGMENT 




COmUN I CATIONS 
CENTER 



DATA 
RECEIVING 
CENTER 



DATA 
PROCESSING 
CENTER 



GROUND SEGfCNT 



DEVELOPfCNTS IN AUTOFiAT I ON /AUTONOMY 

CHARACTERIZED BY DELIBERATE PROGRESS 

WITH NEED 

WITH COMPLEXITY/SOPHISTICATION 

BASED ON MODELS 

KNOWLEDGE OF COMPONENT PERFORMANCE CHARACTERISTICS 
SYNTHESIZED SYSTEM CHARACTERISTICS 

IMPROVED/INCREASED AS MODELS IMPROVED 



PO 

o 



POWER SYSTEFi AUTOMATION EXAMP LES 

SPACECRAFT SHUTDOWN - 1 YR. TIMER 

UNDERVOLTAGE LOCKOUT 

ARRAY ORIENTATION 

SOLAR REACQUISITION 

SHUNT REGULATOR TO CONTROL BATTERY CHARGE VOLTAGE 

TWO-STEP REGULATOR FOR CONTROL/PROTECTION 

SEQUENTIAL SHUNT REGULATION 

MULTI-STEP (V/T CURVES) TO ADJUST FOR TEMPERATURE 

THERMOSTATS TO CONTROL UNDER OVER-TEMPERATURE CONDITIONS 

AUTOMATIC SWITCHING BETWEEN REDUNDANT COMPONENTS/SYSTEMS 

STANDARD POWER REGULATOR UNIT (PARTIAL) 



rilCD CELL DISCHARGE CURVES 









lU 




CAPACITY 



rN3 



niCd battery charge v/t levels 



1.55 f 



CD 



C3 






1.50 



1 . !i5 



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1.30 




TEiiPERATURE (OC) 



STANDARD POWER REGULATOR UNIT 



PEAK POWER TRACKING 
VOLTAGE LIMIT 
CURRENT LIMIT 
STANDBY 



AUTOMATIC (LOAD DEPENDENT) 
V/T SELECTION BY COMMAND 
I SELECTION BY COMMAND 
AUTOMATIC IN ECLIPSE 



ro 

GO 



-pi 



SOLAR ARRAY POWER OUTPUT 



UJ 

o 

ex. 

>- 




ARRAY VOLTAGE 



DEGREES OF AUTOMATION 

ROUTINE OPERATIONS 

CONTROL 
SEQUENCING 

ROUTING MAINTENANCE 

BATTERY CHARGING 
BATTERY RECONDITIONING 

FAILURE HANDLING 

TOLERANCE 
DETECTION 
ISOLATION 
RECONFIGURATION 

FAULT HANDLING 

FAULT TOLERANCE 
FAULT DETECTION 

SELF-TESTING 
MODEL UPDATE 

FAULT CORRECTION 

RECOVERY 
RECONFIGURATION 









POWER SYSTEM AUTONOMY 

SAFE -HOLD AUTONOMY 

UNDERVOLTAGE LOCKOUT 

AWAIT GROUND COMMAND 

TIMED (ON-BOARD CLOCK) RESTART 

LOW VOLTAGE/HIGH CURRENT SAFING 

AWAIT GROUND COMMANDS 

PARTIALLY OPERATIONAL AUTONOMY 

FUSING OF INSTRUMENTS/SYSTEM ELEMENTS 
LOAD SHEDDING 

OPERATIONAL AUTONOMY 

FAULT DETECTION AND ISOLATION PLUS RECOVERY 



CRITICAL ELEMENTS IN AUTOMATION 

KNOWN PERFORMANCE CHARACTERISTICS (MODEL) 
SENSE PERFORMANCE LEVELS (MONITOR) 
COMPARE TO REFERENCES (HEALTH & WELFARE) 
ANALYZE DIFFERENCES (DIAGNOSTIC CAPABILITY) 
DETERMINE ACTION (DECISION CAPABILITY) 
TAKE ACTION (IMPLEMENTATION CAPABILITY) 
UPDATE (ITERATION CAPABILITY) 
GROUND STATION BACKUP (OVERRIDE) 



ro 



CX3 



ANALYTICAL MODELING PROGRAM 



BACKGROUND 

OBJECTIVE - DEVELOPMENT OF RELIABLE POWER SYSTEMS 
PROBLEM - DESIGNS NOT PERFECT 

- HARDWARE NOT PERFECT 

- SOFTWARE NOT PERFECT 

- OPERATIONS NOT PERFECT 

SOLUTION - IDENTIFY AND SOLVE PROBLEMS BEFORE THEY 
BECOME CRITICAL 

- PREDICTION AND PREVENTION OF PROBLEMS 

- VERIFICATION OF OPERATIONAL ADEQUACY 



l£3 



o 



REQUIREMENT - VERIFICATION 

ALL-UP TEST 

UNWIELDY 

COSTLY 

TOO MANY VARIABLES/CONFIGURATIONS 

FURTHER COMPLICATED WITH ON-ORBIT CHANGEOUTS 

SIMULATION 

MUST BE REALISTIC 

MUST ADEQUATELY MODEL WHAT IS SIMULATED 

ANALYSIS 

SIMPLE - TRACTABLE 

ADEQUATE - CAPTURE IMPORTANT FEATURES 

AUTOMATION OF SOME PRE.-LAUNCH OPERATIONS 



FIRST PHASE - REQUIREf^iENTS DEFINITION 



STEP 1 



REVIEW CURRENT APPROACHES 

EARTH ORBITING SYSTEM MODELS 
INTERPLANETARY SYSTEM MODELS 
GENERAL ANALYTICAL PROGRAMS 

DETERMINE PROS (CAPABILITIES) AND CONS (LIMITATIONS) 

IDENTIFY AREAS FOR IMPROVEMENT 

ESTABLISH REQUIREMENTS FOR "IDEAL" MODEL 



00 

ro 



STEP 2 

IDENTIFY PRELIMINARY REQUIREMENTS FOR COMPONENT MODELS 

DETERMINE ADEQUACY OF COMPONENT MODELS 

REGULATION 

SHUNT LIMITER MODELS 

SWITCHING REGULATOR MODELS 

SOLAR ARRAY SWITCHING UNIT MODELS 

GENERATION AND STORAGE 

SOLAR ARRAY MODELS 
BATTERY MODELS 

DISTRIBUTION 

EQUIPMENT 
CABLES 

DETERMINE LIMITATIONS/UNCERTAINTIES IN EACH MODEL 

SPECIFY REQUIRED IMPROVEMENTS 



STEP 3 

IDENTIFY TESTING REQUIRED 

COMPONENTS 
DEVICES 

DETERMINE SEQUENCE 

TESTING 
ANALYSIS 

DEFINE PROCEDURES FOR COMPREHENSIVE POWER SYSTEM 
MODEL DEVELOPMENT 



CONTINUE TO SECOND PHASE 



CO 
CO 



CO 



SUMMARY AND CONCLUSIONS 

1. IT IS IMPORTANT TO SCOPE "THE AUTOMATION PROBLEM" 

WHAT IS TO BE AUTOMATED? 

WHAT DEGREE OF AUTOMATION IS DESIRED? 

NEEDED? 
JUSTIFIED? 
POSSIBLE? 

2. EXPERTISE (KNOWLEDGE) IS BASIC TO AUTOMATION AND MODELING 
IS AN INTEGRAL PART. 

CONSISTENCY OF UNDERSTANDING 
ADEQUACY OF MODEL 
ABILITY TO AUTOMATE 
DEGREE OF AUTONOMY 

3. AUTOMATION SYSTEM WILL ALSO .BE IMPERFECT. 

REQUIRES OVERRIDE CAPABILITY 

REQUIRES RETENTION OF HISTORY/STATUS/HEALTH AND WELFARE 



RECENT ADVANCES 

IN 

AUTOMATION TECHNOLOGY 



R. C. FINKE 
10/28/81 



GO 

on 






THE ION AUXILIARY PROPULSION SYSTEM (lAPS) EMPLOYS A SOPHISTICATED 
AUTONOMOUS SPACE POWER SYSTEM. THE I APS CONTAINS 9 INTERACTIVE POWER 
SUPPLIES. SOME OF WHICH ARE HIGH- VOLTAGE. SOME OF WHICH ARE RAISED TO 
HIGH COMMON MODE POTENTIAL. ALL SUPPLIES ARE VOLTAGE PROGRAMMABLE BY 
TIME TAGGED ON-BOARD COMPUTER COMMAND. DURING THE TWO-YEAR FLIGHT OF 
THE lAPS. THE POWER SYSTEM WILL AUTOMATICALLY ACCOMMODATE FOR OUTAGES. 
ARCING. DEGRADATION OF THE LOAD AND TRANSIENT PHENOMENA. ALL NECESSARY 
COMMANDS TO OPERATE THE lAPS ARE STORED IN RAM. BACKED UP BY PROM. 
GROUND COMMAND CAN MODIFY THE RAM PROGRAM AS THE NEED ARISES. 



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® OBJECTIVES: 

o DEMONSTRATE THRUSTER SYSTEM PERFORMANCE AND 
DURABILITY IN SPACE; 

© MEASURE THRUSTER SYSTEM IN-FLIGHT PERFORMANCE 

© MEASURE PRINCIPAL THRUSTER-SPACECRAFT INTERACTIONS 

o DEVELOP COMMERCIAL SOURCE FOR THRUSTER SYSTEM 

« TRANSFER TECHNOLOGY AND INVOLVE USERS 

® MISSION MODEL 

© 1000 kg, GEOSTATIONARY COMMUNICATIONS SATELLITE 

• 7 YRS N-S STATIONKEEPING (IX/DAY) TO ±0.01° 
9 4 8-cm THRUSTERS CANTED 45° TO N-S 

• IMPLIES 2557 CYCLES OF 2.76 hrs FULL THRUST OPERATION 
(= 7055 TOTAL hrs) FOR EACH THRUSTER 

• DUAL THRUSTER OPERATION 



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a/<£ips 






J 



-^ co/^r/zACTo/z 



s/c r£:sr c£/rr££.(src) 



/^A/£- T'/iP£:s^ 






O 



MA/L TAP^rs 



i_ 



LcJZC 






L 



— ! 



_i 






PEU REQUIREMENTS 
(TS-200, REV. A) 



A. INPUT VOLTAGE RANGE: 50 VDC TO 90 VDC 

B. MAXIMUM INPUT irOWER: 200 W DC 

C. PEU EFFICIENCY: '& 75% 

i). PEU SIZE (MAXIMUM): 17. o' INCHES (LENGTH) BY 9.0 INCHES (WIDTH) BY 4.5 INCHES (HEIGHT) 

E. PEU WEIGHT: ^16.6 POUNDS 

F. PEU SUPPLY OUTPUTS PER TABLE 3-1. TS-200 

G. PEU TELEMETRY OUTPUTS PER TABLE 3-2. TS-200 (5 V FULL SCALE) 
H. PEU SUPPLY OUTPUTS. DC SUPPLIES, RIPPLE: < 10% PEAK 

I. PEU SUPPLY OUTPUTS SHALL HAVE INTERNAL OVERLOAD PROTECTION 

J. PEU SHALL PROVIDE SCREEN OVERLOAD OUTPUT TO DGIU 

K. PEU PULSER OUTPUTS TO BE ^ 5 KV INTO 1200 ppf OR 100 K OHM LOAD 



PEU BLOCK DIAGRAM 



70 V INPUT 



u 



VINE 
RLTER 



UNE 
REGUIATOR 



48VDC 



CONTROL 



DISCHARGE 
SUPPtY 



CONTXOL 



SCRfEN 
SUPPl-Y 




CONTROL 
XC 
X'< 



NEL.TRAIIZER 
VAPCXIZER 
HEATER 
MA 



TO 
lOAO 



CONTROL 
X X' 



TO 
-MAIN 




NEUTRAU2ER 

KEEftR 

MA 



111 



NEUniAUZER 

CATHODE 

HEATER 

MA 



HIGH 
VOLTAGE 

PtJLSER 

CONTROL 



TO 
NEUTIlAUZft 



TO 
LOAD 



ACaLERAIOR 



-300 V 
TO LOAD 



CO 






I APS - S/C INTERFACE 



POWER BUS 

ONE COMMAND CHANNEL PER T/S 

ONE TELEMETRY CHANNEL PER T/S 

ONE TELEMETRY CHANNEL FOR DIAGNOSTICS 

T/S FUNCTIONS CONTROLLED BY TIME TAGGED 
COMMANDS FROM S/C 



10676-19 



DCIU 



SPACECRAFT 



SERIAL 
TELEMETRY 



SERIAL 
COMMAND 
(TIME- 
TAGGED) 




HAMMING- 
CODE ERROR 
CORRECTION 



ADC 



MUX 



DAC 



MUX 



J 



PEU 



THRUSTER 
AND GIMBAL 



ANALOG 
TELEMETRY 



DIGITAL 

ON/OFF 

COMMAND 



ANALOG 
COMMAND 



2 MHz 
CLOCK 


1 ► 




> 



NINE 
VOLTAGE- 
PROGRAMMABLE 
POWER 
SUPPLIES 



POWER 



TIME 






APRIL 1981 



-p. 



PHILOSOPHY MEOUISEEIENTS 



10816-8 



® EXECUTE ALL NORMAL THRUSTER FUNCTIONS ON 

SINGLE COMMAND 

© MAINTAIN THRUSTER ON DESIRED OPERATING 
POINT 

© PERFORM FAILURE WORKAROUNDS 

o AUTOMATIC (TEMPERATURE SENSORS) 

e GROUNDENABLED (CATHODE HARDSTARTING) 

^PROVIDE T/M AND S/C INTERFACE 



APRIL 1981 



COMTSOL PMILOSOPMY AFPIIOAC 



© STATE DIAGRAM: OPERATING MODES 

© THRUSTER MONITOR 

« MODE MAINTENANCE 

<» FAULT /FAILURE SERVICE 

© MODE-TRANSITION PACKAGES 

o EXECUTIVE 

« COMMAND AND T/M PROCESSING 
o HOUSEKEEPING FUNCTIONS 



10816-9 



APRIL 19S1 



-P=" 



4=. 
CO 




FULL THRUST 
REDUCED THRUST 



JL 



STEADY STATE 
STANDBY 



AiMTI-FREEZE 



OFF 



NEUTRALIZER 
OFF 



Ml Ml MUM 
STANDBY 




SYSTEM 
MAINTENANCE 



ii 



DK 

MAINT 




NK 
MAINT 



CONDITIONING 



BEAM-ON STATES 



BEAM STANDBY 
IDLE STATES 



CATHODE 
DISCHARGE 
MAINTENANCE 
STATES 



NO-CATHODE-ON 
STATES 

APRIL 1981 



1-SECOND 
INTERRUPT 



-> 

lO 



10316-11 



EXECUTIVE 



©COMMAND PROCESSING 
©T/M UPDATE 
©RAM REFRESH 
©TIME MAINTENANCE 
©WATCHDOG TIMER RESET 



THRUSTER MONITOR 



©BEAM-CURRENT CONTROL 
©FAULT/FAILURE RECOVERY 



MODE MANAGER 



TRANSITION TASKS 



MODE TRANSITIONS 
> FAULT RECOVERY 



APPLICATION ROUTINES 



APRIL 1981 



HIEMAHCHY 



en 
O 



TliMUSTEE MOWITOR 



© DETECT FAULT/FAILURE CONDITIONS 

• SET FLAGS FOR TRANSITION ROUTINES 
® INVOKE RECOVERY ROUTINES 

© CONTROL BEAM CURRENT 

® ADJUST DISCHARGE CURRENT TO GIVE: 

- NOMINAL THRUST 5 mN (1.13 mlb) 

- REDUCED THRUST 4.5 mN (1.00 mlb) 



1(5816-12 



APRIL 1981 



ACCOMBIODATEP B¥ COKTIlOLLEIi 



10816-14 



FAULT/FAILURE 


RECOVERY 


DV OR NV TEMP SENSOR 
FAILURE 

DK OR NK HARDSTART 

DK OR NK EXTINCTION 

DISCHARGE OR NEUTRALIZER 
FLOODING 

^D' ^DK' ^^ ^NK INSTABILITY 
OR TELEMETRY FAILURE 

I^K OR Ink TELEMETRY 

FAILURE 

GRID SHORT OR HIGH l^ 

EXCESSIVE HIGH VOLTAGE 
RECYCLING 

EXCESSIVE POWER 
CONSUMPTION 

LOW BUS VOLTAGE 
LOSS OF LOGIC CONTROL 
RAM BITFLIP 


AUTOMATIC TIME-BASED STARTUP 
WORKAROUNDS; FIXED SETPOINT 
VAPORIZER OPERATION 

EXTENSIVE HARDSTART ALGORITHMS; 
SHUTDOWN TO MAINTENANCE STATE 

AUTOMATIC RELIGHT AND STATE RECOVERY 
AUTOMATIC ANTIFLOODING ROUTINES 

TEMP OR FIXED SETPOINT VAPORIZER 
OPERATION 

IGNITION TEST ON VOLTAGE 

AUTOMATIC HIGH VOLTAGE RECYCLE 
SHUTDOWN FOR GROUND RESTART 

HIGH VOLTAGE TURNOFF + AUTOMATIC 
RECOVERY ROUTINE 

SHUTDOWN AND RESET FOR GROUND 

RESTART 

SHUTDOWN VIA WATCHDOG TIMER AND 

RESET FOR GROUND RESTART 

PERIODIC HAMMING CODE TEST AND REFRESH 



APRIL 1981 






>APv5PLE MO!DE TEABJSITIO 
FF TO FULL Tlf MUST 



10815-15 



(^ 


PART V- 




HEAT CATHODES 

AND 

VAPORIZERS 




MAINTAIN AT 

IGNITION 

TEMPERATURE 

3MIN 




IGNITE 








CATHODES 














1 r 


WAIT 
3M!N 




ANTl FLOOD 




RUN3MIN 

AT HIGH 

CURRENT 




TURN ON 
DISCHARGE 








1 


r 












/transitionN 

v. COMPLETE^ 


BEAM 




A.MTI FLOOD 




ADJUST 

DISCHARGE 

CURRENT 


^ 


or 


M 









APRIL 1931 



MdERSM, OFEl 



10316-2 



CO 



1A 



5oy 





lOOmA 




500mA 




SOV 




SOV 




5VA 






PREHEAT 

L 



'^WARM-UP-*- 



DK !G\.T10IM 



\ 



-/^ 





97° 


167° 


206° 


219° 


242° 


250° 




t 


» 


t 


f 


t 


» 


— ' 















NK iGNlTiON 



317° 291° 

i i 



257° 



234° 265° 



i I 

296° 309° 



15 



20 



TIMLnai 



t 

247° 



FULL THRUST 
BEAM ON L 



t 



242°-247° 

ANTIFLOOD 



» 

252° 



i 
255° 



i 
247° 




APRIL 1981 



■ -Pi 



TEST COMHGUMATIOWI 



10815-17 





COMPONENT: THERMAL ENViHONMENI 1 

5 


TEST 


THRUSTER 


PEU 


DCIU 


PREQUALIFICATION 


EM: 

THERMAL 
VACUUM 


EM: 

THERMAL 

VACUUM 


BREADBOARD: 
AMBIENT 


FLIGHT CHECK-OUT 


FLIGHT: 

THERMAL 
VACUUM 


FLIGHT: 

AMBIENT 


BREADBOARD: 

AMBIENT 


QUALIFICATION 


EM: 

THERMAL 
VACUUM 


EM: 

THERMAL 

VACUUM 


FLIGHT: 

AMBIENT 

i 



APRIL 1981 



corjCLUsio?4S 



1C3815— 19 



© CONTHOL SOFTWARE SUCCESSFULLY 
IMPLEMENTED IN CONTROLLER 



© CONTROLLER SUCCESSFULLY DEMONSTRATED 

WITH FLIGHT THRUSTERS 



o COMPREHENSIVE CONTROLLER CAPABILITY 
DEMONSTRATED IN EXTENSIVE TESTING 



APHiu ;9at 



en 






AUTOMATION 

REQUIRES DETAILED KNOWLEDGE OF: 

- SYSTEM REQUIREMENTS AND FUNCTION 

- SYSTEM ELEMENTS 

CHARACTERISTICS 
INTERACTIONS 

CAN ONLY BE ACCOMPLISHED AFTER SUFFICIENT 
UNDERSTANDING OF SYSTEM CHARACTERISTICS 
EXISTS 



AUTOMATION TECHNOLOGY 
FOR POWER SYSTEM MANAGEMENT 



Dr. Ronald L. Larsen 
NASA Headquarters 
October 28, 1981 



en 



U1 

00 



POWER SYSTEM COST REDUCTION THROUGH AUTO/VIATION 



90 



70 



60 



60 



MONITORING 
AND CONTROL 
COSTS M$- 1980 40 



30 



20 



10 













J 










J 


/ 








^ 








A 


f 








A 


f 








y 


y 










/ 
























UNA 


ATTEND 


1 ■ 

•ED OPERATION (PMS) _ 


1 1 T r- 1 1 1 



Ref: TRW PMS Study 



6 10 15 20 25 30 

SATELLITE OPERATICt^AL LIFE-YEARS 



FUNCTIONS OF AN EXPERT 

INTERPRETATION - ANALYS IS OF DATA 

DIAGNOSIS - IDENTIFICATION OF FAULT 

PRED ICTION - FORECAST FUTURE FROM MODEL 

MONITORING - SET OFF ALARMS, AVOID FALSE ALARMS 

PLANNING - PROGRAM ACTIONS TO ACHIEVE GOALS 

DESIGN - PLANNING TO CREATE OBJECTS 

EXPLANATION - MAK ING UNDERSTANDABLE 






O 



EXPERT SYSTEMS 



MODEL A PERSON'S UNDERSTANDING OF A SYSTEM 
RATHER THAN THE SYSTEM ITSELF 



Ref: Hayes -Roth, F. , "A Tutorial on Expert Systems: Putting Knowledge to Work," 
IJCAI-81 



DEFIMING "EXPERT SYSTEIVIS:' 



1 . The field of expert systems investigates methods 
and techniques for constructing man-machine 
systems with domain-specific problem-solving 
expertise 

2. Expertise consists of knowledge about a domain, 
understanding of domain problems, and skill at 
solving such problems 






A QUICK HISTORY 



^^HEARSAY-II •••►AGE/HEARSAY-III 
(speech HEARSAY-lC 

understanding) ^^ HARPY 

, , , PROSPECTOR 

(geology) 



/ ^PUFF 



EMYciNr:;^ 

MYCIN ^^^ ROSIE 

(medicine) ^"^ •• • TEIRESIAS 

IIMTERNIST— ^ •••► 

(symbolic mathematics) 
SAINT-^-«**SIN—^ •••MATH LAB— ►•••MACSYMA-^*** 



CASIMET— •-•EXPERT — ••• 

(organic chemistry) 

— — DENDRAL — •••META-DENDRAL ^ ' 

1965 1970 1975 1980 



WHAT DO EXPERT SYSTEMS DO? 

1 . Use expert rules to avoid blind^search 

2. Reason by manipulating symbols 

3. Grasp fundamental domain principles and 
weaker general methods 

4. Solve complex problems well 

5. Interact intelligibly with users 

6. Interpret, diagnose, predict, instruct, 
monitor, analyze, consult, plan or design 



CO 






THE BASIC IDEAS 

1 . Knowledge = Facts + beliefs + heuristics 

2. Success = Finding a good-enough answer with the 

resources available 

3. Search efficiency directly affects success 

4. Aids to efficiency: 

- The quality and generality of knowledge 

- The rapid elimination of "blind alleys" 

- The elimination of redundant computation 

- The speed of the computer 

- The use of multiple sources of knowledge 

5. Problem complexity increases with: 

- Errorful or dynamically changing data 

- The number of possibilities to be ruled out 

- The amount of effort required to rule out 

a possibility 



ll\!SfDE MYCm 

O Problem representation 

!One or more patients, 
with one or more symptoms, 
with one or more diseases, 
with one or more treatments 

© Table of operators: If-Then rules 

If there is <condition> 

[and/or <condltion>]... 
Then there is suggestive 

evidence (.8) of <disease> 



O Control 



(J1 



1. Backchaining 

2. Exhaustive 

3. Certainty factor calculus 
for conflict resolution 



COPING WITH COMPLEXITY 



Small Search Space 
Reliable Data and Knowledge 



I 



Unreliable Data 
or Knowledge 



Combining Evidence 
from multiple sources 
Probability Models 
Fuzzy Models • 
Exact Models 



No evaluator for 
Partial Solution 



Fixed Order of 
Abstracted Steps 



6 



Domain does not admit 
Fixed Sequence 



[Abstract Search Space 



Subproblems Interact 






Constraint Propagation 
Least Commitment 



8 
I Guessing is Needed 



I Plausible Reasoning 
j Dependency -Directed 
Backtrackinn 



Exhaustive Search 

Monotonic Reasoning 

Single Line of Reasoning 



Time-Varying Data 



State-triggered 
Expectations 



Big Search Space 



Hierarchical 
Generate and Test 



11 



Single model too weak 



Multiple Lines of 
Reasoning 



10 



Knowledge Base 
Too Inefficient 



Choice of 

Data Structure 
Compilation 
Cognitive Economy 



Diverse Knowledge 
Sources 



Heterogenous Models 
Opportunistic Scheduling 
Variable-Width Search 



66 



EXAMPLE 
BATTERY CHARGE CONTROL 



VOLTAGE/TCMPERATURE CHARACTERISTICS 

FOR MULTIPLE LEVEL NICKEL-CADMIUM 

BATTERY CHARGER 



*10 +20 

TEMPERATURE - DEGREES CENTIGRADE 



NO. 8 







00 



THE PUNCH-LINE 



An Expert System (as a human expert) 

blends fundamental knowledge, 

practitioners' wisdom, and skill 

in the controlled application 

of data, knowledge, and tools 



SPACE POWER SYSTEM AUTOMATION WORKSHOP 

MARSHALL SPACE FLIGHT CENTER 

28/29 OCTOBER 1981 

SPACECRAFT SYSTEM/POWER 
SUBSYSTEM INTERACTIONS 



Chris Carl 
MANAGER, SPACECRAFT SYSTEMS ENGINEERING SECTION 

Jet Propulsion Laboratory 
Pasadena, California 



en 



o 



INTRODUCTION 



t TRENDS IN AUTOMATION 

• CANDIDATE SYSTEM REQUIREMENTS/POLICIES 

• SYSTEM CONSTRAINTS ON SUBSYSTEM AUTOMATION 

• FAULT PROTECTION/CORRECTION EXAMPLES 
CONCLUSIONS 



DRIVERS FOR INCREASED 
ON-BOARD AUTOMATION 



t GROUND COSTS 

t RESP0NSET!MEREQU1REDIS<C 2 WAY-LIGHT TIME 

t BLIND OPERATIONS 

• MISSION-CRITICAL ACTIVITIES DURING ENCOUNTER 

LONG aiGHT TIMES 

§ HIGHLY VISIBLE, ONE-SHOT PROGRAMS 



-~4 



AUTONOMOUS FEATURES 



MARINER IV-X 

» SUN ACQUISITION 
» STAR ACQUISITION 



REDUNDANT POWER 
CHAIN SWITCHOVER 



• AUTOMATIC SEQUENCE 
IV-VIl 



• POWER SHARE 



VIKING ORBITER 

SUN ACQUISITION 
STAR ACQUISITION 



REDUNDANT POWER 
CHAIN SWITCHOVER 



REDUNDANT TRANSMIHER 
SWITCHOVER 

COMMAND LOSS 



BAHERY OVERTEIViP 



POWER SHARE 



PRESSURE REGULATOR 
FAILURE MONITOR 

ATTITUDE CONTROL 
POWER CHANGEOVER 

COMPUTER ERROK 



MO I POWER TRANSIENT 



VIKING EXTENDED 
MISSION 



BAHERYFAIL 
PROTECTION 



BATTERY CHARGE 



RECVR PROTECT 

STOP A/C GAS LEAKS 

SCIENCE PROTECTION 

DOWNLINK OFF 

ROLL DRIFT 
MODE ENTRY 

STAR TRACKER 
PROTECTION 

ENGINE MONITOR 

AUTOMATION 
FUNCTION MONITOR 



VOYAGER 

SUN ACQUISITION 
STAR ACQUISITION 



REDUNDANT INVERTER 
SWITCHOVER 



REDUNDANT TKANSMIHER 
SWITCHOVER 

BACK-UP AUTOMATIC 
MISSION 

COMMAND LOSS 



IRS PWR 



PWR CHECK 



THRUSTER MANAGEMENT 
GYRO MANAGEMENT 
COMPUTER ERROR 
TURN SUPPORT 
AACS PROCESSOR SWAF 
AACS HYBIC SWAP 
PLATFORM SAFING 



GALILEO 



SUN ACQUISITION 



REDUNDANT INVERTER 
SWITCHOVER 



REDUNDANT TRANSMIHER 
SWITCHOVER 

COMMAND LOSS 



PWR CHECK 



THRUSTER MANAGEMENT 
GYRO MANAGEMENT 
COMPUTER ERROR 
TURN SUPPORT 
AACS PROCESSOR SWAP 
PLATFORM SAFING 
TEMPERATURE CONTROL 
PROPULSION SAFING 
SEQUENCE RESTART 
SCIENCE PROTECTION 






CANDIDATE SYSTEM REQUIREMENTS/POLICIES 



GENERAL REQUIREMENTS 

• THE SPACECRAFT SHALL OPERATE W/0 GROUND CONTROL 
FOR TBD DAYS W/0 DEGRADATION 

• BLOCK REDUNDANCY 
•FUNCTIONAL REDUNDANCY 

• Hi RELIABILITY COMPONENTS 

• THE SPACECRAFT SHALL OPERATE W/0 GROUND CONTROL 
FOR TBD DAYS WITH LESS THAN TBD % DEGRADATION 

• GRACEFUL DEGRADATION 

• TRANSPARENCY OF AUTOMATED ACTIVITIES 

• RELIABLE, TRANSIENT-FREE RECONFIGURATIONS 

• MEMORY "KEEP ALIVE" 

• AUDIT TRAIL OF AUTOMATED ACTIVITIES 

• STORE ACTIVITIES 

• MEMORY READOUT 

• FLAG SET 

• GROUND SYSTEM OVERRIDE 

• RESTART 

• REP ROG RAMMING 






CANDIDATE SYSTEM REQUIREMENTS/POLICIES 



RELIABILITY 



NO SINGLE HARDWARE FAILURE SHALL RESULT IN LOSS 
OF MORE THAN ONE INSTRUMENT OR >50% OF ENGINEERING 
DATA 

• BLOCK REDUNDANCY 

• FUNCTIONAL REDUNDANCY 

• LOAD MANAGEMENT 

• FUNCTIONAL INDEPENDENCE 

THE CENTRAL DECISION-MAKER SHALL BE THE MOST 
RELIABLE ELEMENT 

PROCESSORS SHALL PERFORM SELF-TEST PRIOR TO 
ISSUING ANY COMMANDS 



CANDIDATE SYSTEM REQUIREMENTS/ POLICIES 



FAULT PROTECTION 

• FAULT RECOVERY TO AN UNAMBIGUOUS STATE 

• POWER ON RESET 

• FAULTS DETECTED/CONFIRMED BY INDEPENDENT SOURCES 

• HIGH RELIABILITY SENSORS 

• MULTIPLE SENSORS 

• VOTING 

• FAULT PROTECTION AT LOW LEVELS 

• SENSORS AND SWITCHING AT LOWEST PRACTICAL 
ELEMENT 

• FALSE ALARM PREVENTION 

• HARDWARE/SOFTWARE TOLERANCES TO BE SET AT 
"UNACCEPTABLE^' PERFORMANCE 









CANDIDATE SYSTEM REQUIREMENTS/POLICIES 



SYSTEM STATES 

• SPACECRAFT STATE PQSITIVELY IDENTIFIABLE FROM 
TELEMETRY 

• STATUS WORDS 

• AUTOMATED ACTIVITIES REVERSIBLE 

• ANY SPACECRAFT STATE ACCESSIBLE AND 
COMMANDABLE 

SYSTEM TEST 

• SYSTEM TEST PLANS SHALL BE PREPARED EARLY IN 
DEVELOPMENT TO HELP VALIDATE AUTOMATED ROUTINES 

• SUBSYSTEMS SHALL HAVE EARLY DEFINITION OF 
AUTOMATED OPERATIONS 



CANDIDATE SYSTEM REQUIREMENTS/POLICIES 



SYSTEM TEST 



• ALL UNIT OR BLOCK REDUNDANT ELEMENTS SHALL PROVIDE 
ACCESS FOR CHECKOUT, CALIBRATION AND REPROG RAMMING 



• TEST PORT FOR FAULT INJECTION AND RESPONSE 



• MEMORY ACCESSIBILITY 



• GROUND/IN-FLIGHT VISIBILITY 






CO 



CANDIDATE SYSTEM REQUIREMENTS/POLICIES 



SOFTWARE 



• TELEMETRY SHALL PROVIDE INFORMATION TO 
DETERMINE THE OPERATIONAL ACTIVITY AND 
STATUS OF FLIGHT SOFTWARE 

• PROTECTION SHALL BE PROVIDED AGAINST WRONG 
OR INVALID COMMANDS 

• MULTI -COMMANDS 

• HANDSHAKE 

• ECHO 

• PARITY 

• CODED COMMANDS 



CANDIDATE SYSTEM REQUIREMENTS/POLICIES 



MEMORY 



• SUBSYSTEMS WITH VOLATILE MEMORIES SHALL ASSURE 
THAT DIRECT MEMORY ACCESS IS OPERATIONAL AT POWER 
ON RESET 



COMPUTER MEMORY MARGINS SHALL BE PRESERVED 

•MEMORY MANAGEMENT DURING DEVELOPMENT AND 
OPERATIONS 



• ON-BOARD COMPUTER MEMORIES VERIFIABLE 
•MEMORY READOUT 
•CHECKSUM 



-J 



00 

o 



SYSTEM CONSTRAINTS 
ON SUBSYSTEM AUTONOMY 



AUTOMATION IS NO N- INTERACTIVE WITH THE SYSTEM IF IT DOES NOT: 

• AFFECT THE STATE OR DATA TAKI NG OF MORE THAN ONE SUB SYSTEM 

• AFFECT THE DOWNLINK MAR GIN, TELEMETRY FORMAT OR RATE 

• AFFECT 1ST ORDER GROUND PROCESSING CONFIGURATION 

t INCREASE CENTRAL COMPUTER PROCESSING OR BUS TRAFFIC OVER 
ALLOCATIONS 

• CHANGE STORED SEQUENCES 

• ALTER AHITUDE CON"mOL OR STABILITY MARGINS 
a INCREASE POWER DEMANDS ABOVE MARGINS 

ALTER THERMAL BALANCE 

• IMPACT SYSTEM INTERFACES 



SYSTEM CONSTRAINTS 
ON SUBSYSTEM AUTONOMY 



AUTOMATION IS NON- INTERACTIVE WITH THE SYSTEM IF IT DOES NOT: 

t ADVERSELY IMPACT SPACECRAFT SYSTEM LIFETIME, 
RELIABILITY, OR PERFORMANCE 

t ADVERSELY IMPACT SYSTEM OR SUBSYSTEM SAFETY 

• RESULT IN SELECTION OF SYSTEM REDUNDANT RESOURCES 

• IRREVOCABLY CHANGE SPACECRAFT STATE 



CX3 



00 



FAULT PROTECTION/CORRECTION EXAMPLES 

VIKING SHARE MODE CORRECTION 



• FUNCTION 

TURN OFF LOADS WHEN POWER SUBSYSTEM IS UNABLE TO BOOST 
OUT OF AN UNINTENDED SOLAR PANEL/BATTERY SHARE CONDITION 
WHILETHE SPACECRAFT IS SUN ACQUIRED 

• STRATEGY 

f COMPUTER COMMAND SUBSYSTEM (CCS) COUNTS BOOST PULSES 
FROM REDUNDANT SHARE.MODE DETECTORS WITHIN POWER AND 
TURNS OFF LOADS IN PAIRS EACH TIME THATTHE NUMBER OF 
PULSES IN A GIVEN TIME PERIOD EXCEEDS A PREDETERMINED VALUE 

• FOR MISSION PHASES OTHER THAN MARS ORBIT INSERTION, THE 
CCS COMMANDS THE SPACECRAF TO A SAFE STATE PRIOR TO 
EXECUTI NG THE SHARE MODE CORRECTION RESPONSE 



Cih9 



FAULT PROTECTION/CORRECTION EXAMPLES 

VIKING SHARE MODE CORRECTION 




!7 

1 



ACS 




SHftRE/VfOOE PULSES 

BOOST COIWBITSI 
ENABLE D[SABl£ 



SQtAR ARRAY 
WPAIUELS 
62Q WATTS 
RATmG 
(AT MARS) 

T 



2&-5IVDC 

T 



RAW PQWe? BUS 



I 



-HN- 



1 



K3QST 
CQWSTK 



T 



SHARE 
WQDE 
DblhCrOR 
(REDUNBAND 



-I*- 



27.4-32.5 V DC 
^ 



BATTERY 
25 CELLS 

RATING 

— X 



BATTERY 
CHAR(^ 
a.7T, 2. 3 AMP 
I RATII^G 



BATTERY 
25 CELLS 
3ffA/WP-HR 
RATING 

— IT 



BATTERY 
CHARGS? 
Q.77, 2, 3 AMP 
RATING 



^ 



~ 32-39 VEJC 



Jr Pmm REflRN 



U^JREGULATED 
■ .^WER 



REGULATED 

PQWER 



L 



PQWISIS 



QQ) 



VOYAGER "PWRCHK" EXAMPLE 

FUNCTION -PROTECTS AGAINST: 

INTERNAL POWER FAILURES 

t EXCESS LOAD POWER DEMAND 
• STRATEGY- IF INTERNAL POWER FAILURE — 

SWITCH TO REDUNDANT ELEMENTS 

BRING MISSION-CRITICAL SYSTEMS & SEQUEIVCES BACK OH LINE 

SWITCH TO LOW RF POWER 

WAIT FOR GROUND ASSISTANCE 

IF EXCESS LOAD DEMAPID — 

SHED ALL [^N-CRlirCAL LOADS (INCLUDIIVG SC!E!VC9 

TURN ON REPLACEMENT HEATERS 

SWITCH TO LOW RF POWER 

WAIT FOR GROUND ASSISTANCE 



VOYAGER POWER SUBSYSTEM 
SIMPLIFIED BLOCK DIAGRAM 



ESSENTIAL POWER 



FDS 



INVERTER SYNC 



TELEMETRY 



J 



RTGCASETEAAP 
RTG OUTPUT VOLT 
RTG OUTPUT CURRENT 
D C BUS VOLT 
SHUNT REG CURRENT 
D C BUS CURRENT 
2.4 kH3 INPUT CURRENT 

2.4 kz 2.4 kHz 
2.4 kHz! NPUT VOLTAGE 
2.4 kHz OUTPUT VOLTAGE 
INVERTER STATUS 
SHUNT REG VOLTAGE 
SHUNT REG TEMP 
BATTERY TEMP 



POWER 
SUBSYSTEM 



1— 

I— 

_i 

o 

> 

LU 
CI 



I— 
< 
I— 
CO 

Q£ 
UJ 

\— 

UJ 

> 



Q 



o 
o 

on 






f2 



CCS 



T 






2.4kHz50VRMS 



ACl 



30 VDC REG 



DCl 




NON-ESSENTIAL POWER 



2.4kHz 50VRMSAC2 



RF RCVR 
AACS GYROS 
INV SELECT 



TOLERANCE 

DETECTOR 

TRIP 



30 VDC DC2 



S-BAND EXC 
S-BAND TWTA 
S-BAND SEL 
S-BAND XMTR 
X-BAND XMTR 
X-BAND TWTA 
X-BAND EXC 
AACS HTRS 
PROP HTR 
CRS 

PRA ANT 
PPS 
REPL HTRS 



MDS TMU 

PYRO TUVl 

PRA 

PWS 

LECP 

PLS 

UVS 

MAG 

ISSNA 

ISSWA 

MIRIS 



CCS A 
CCSB 
AACS PROC 
ASCS HYBK 1/2 
AACS CST 1/2 
SUN SHUHER 
PYRO PSU A/B 



SCIENCE 
INSTRUMENTS 



CO 



00 
CTl 



CONCLUSIONS 



• DEVELOP SYSTEM REQUIREMENTS AND DEFINE SYSTEM 
INTERFACES 

• DEVELOP RELIABLE SENSORS, ALGORITHMS AND EFFECTORS 

• DEVELOP VALIDATION AND TEST METHODOLOGY 



TECHNICAL ISSUES IN POWER 

SYSTEM AUTONOMY 
FOR PLANETARY SPACECRAFT 



00 



Fred C. Vote 

Electrical Power and 
Propulsion Section 

Jet Propulsion Laboratory 

October 28, 1981 



00 

oo 



Agenda 



EVOLUTION OF SPACECRAFT POWER SYSTEM REQUIREMENTS 



OVERVIEW OF AUTOMATED SPACECRAFT POWER MANAGEMENT 
(ASPM) PROGRAM 



FUTURE PLANETARY POWER SYSTEM REQUIREMENTS 



TECHNICAL/ SYSTEM-LEVEL ISSUES IN PLANETARY POWER 
SYSTEM AUTONOMY 



RECOMMENDED POWER SYSTEM AUTOMATION OBJECTIVES 



Evolution of Planetary 
Spacecraft Power System Requirements 



PUNETARY POWER SYSTEM REQUIREMENTS HAVE BEEN DRIVEN 
BY MISSION/ SPACECRAFT REQUIREMENTS AND DURATION 



SPECIFIC POWER 



RELIABILITY 



FAULT RESPONSE TIME 



FLEXIBILITY 



AUTONOMY 



00 

«3 



U3 
O 



Specific Power of Power Subsystems 



8 



SPECIFIC 
POWER, 4 
W/kg 

3 



60 



POWER SOURCES INCLUDED 



< 

z 

< 



o z: 



en 






O 

> 



< 
>- 
o 

> 



o 

< 



2 MJ 

2S 
»- >- 
<C CO 
^ 00 
UJ 3 

uJ O 



1 



I 



X 



64 



68 



72 76 

YEAR OF LAUNCH 



80 



84 



88 



Specific Power of Power Subsystems 



30 f- POWER ELECTRONICS 



25 



SPECIFIC 

POWER. 

W/kg 



20 



15 



10 



(O 



60 



a: 



5L^ 



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m 



a. 
ui 



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._ UJ 



o 



2 



i t I I I 1 L 



64 



68 72 76 

LAUNCH YEAR 



80 



84 



88 






Power Subsystem Reliability Requirements 



REQUIRED MISSION DURATION 



ROUND TRIP LIGHT TIME AT PLANET 



CO 

I 



7r 
6 
5 
4- 

3- 

2 

1 





I 



CO 
txJ 



O^ 



700 
600 
500 
400 
300 
200 
100 




NEPTUNE 



URANUS • 



UJ 

o 

<: 

Del 



^0 



< 



2S 

Of 03 



UJ 

o 

o o 
> > 



CO 



o 

y 

< 

o 



LLi 

o 



CO 



£ 



LU 

o 



Q^ 



LU 



< 



SO 

o 

> 



on 

LU 
O 

I ^ 



2C^ 

< CO 
O^ CQ 
LU Z3 

o S'« 

< 2| 



Fault Tolerance of Power Subsystems 






FAULT TOLERANT 
COMPUIERS 



COMMAND 
VERIFICATION 



MAINTENANCE OF 
MAXIMUM PERFORMANCE 



FUNCTIONAL 
REDUNDANCY 



LOAD SHEDDING 



AUTOMATIC OPERATION 
ON SOLAR ARRAY 



FAULT ISOLATION 



ELIMINATION OF SINGLE 
POINT FAILURES 



BLOCK 
REDUNDANCY 







Power Subsystem Flexibility Requirements 



FLEXIBILITY REQUIRED 



700 r 



600 



500 



400 



MEASURED AS NUMBERS OF 

LOADS 

TELEMETRY WORDS 300 |- 

SEPARATE COMMANDS 
FOR POWER SUBSYSTEM 

200 h < e. = 



GALILEO 



ic«hiiiiTi 




HOADS 



SEPARATE 
COMMANDS 




TELEMETRY 
WORDS 



68 72 76 

LAUNCH YEAR 



Power Subsystem Without 
Onboard Computation Capability 








POWER 
SOURCE 










UNREGUUTED 
POWER 




SPACECRAFT 

COMMAND 

SUBSYSTEM 


COMMANDS 


POWER 
SUBSYSTEM 


REGULATED AC ^ 


POWER 
USERS 




AND DC POWER 


1 

1 




1 DATA 






COMMANDS 

FROM 

GROUND 




SPACECRAR 

TELEMETRY 

SUBSYSTEM 






4 

1 

1 

1 




1 
1 

1 

♦ 






DATA 
ANALYSIS 
ON GROUND 


4^^ i^B ^am ^am ^^ ■■• ■ 


DATA RECEIPT 
ON GROUND 










Power Subsystem With 
Onboard Computational Capobility 




ONBOARD 
COMPUTER 
AND COMMAND 
GENERATOR 






POWER 
SOURCE 



{UNREGULATED 
POWER 



SPACECRAFT 

COMMAND 

SUBSYSTEM 



COMMANDS 



POWER 
SUBSYSTEM 



I 



REGULATED AC 



AND DC POWER 



^^ 




SPACECRAFT 
TELEMETRY 

SUBSYSTEM 

1 



• IMPROVED PERFORMANCE 

• FAULT TOLERANCE 

• GRACEFUL DEGRADATION 



Overview of Automated Spacecraft Power 
Management System (APSM) Program 



U3 

^-4 



• APSM PROGRAM 

6 - Year Program (1975-1981) 
$1.9P1 

t OBJECTIVES 

DEVELOP TECHNIQUES AND DEMONSTRATE TECHNOLOGY TO PROVIDE RELIABLE 
AUTOMATED POWER SUBSYSTEM MANAGEMENT FUNCTION WITH CAPABILITIES OF: 

• PROVIDING ACCURATE ASSESSMENT OF POWER SUBSYSTEM PERFORMANCE 

• DETECTING AND CORRECTING EQUIPMENT FAULTS 

• MANAGING USER LOADS 

• EVALUATE THE PERFORMANCE OF AUTOMATED POWER SUBSYSTEM MANAGEMENT 
AS APPLIED TO THE SOLAR ARRAY-BATTERY POWER SUBSYSTEM USED ON THE 
VO 75 SPACECRAR 

• SERVE AS "PILOT" AUTOMATED POWER SYSTEM 



00 



APSM Approach 



• DEVELOP UPON A STATE-OF-THE-ART PLANETARY POWER SUBSYSTEM 

• UTILIZE THE BREADBOARD VO 75 POWER SUBSYSTEM 

• CONTRACTED EFFORT FOR CONCEPT DEFINITION AND IMPLEMENTATION 
(MARTIN MARIETTA) 

t TEST AND EVALUATION BY JPL 



VO 75 Power Subsystem 



BOOST 
CONVERTER 




REDUNDANT 
BATTERIES 



I 



REDUNDANT 

BAHERY 

CHARGERS 



V UNREGULATED 



DC POWER 



■^' 



REDUNDANT BOOST 
REGULATOR AND 
INVERTER CHAINS 



REGULATED. 



AC POWER 



USER LOADS 

INDIVIDUALLY 
FUSED 

1 1 1 1 1 



AC AND DC POWER 
DISTRIBUTION 



us 



o 
o 



VO 75 Power Subsystem 

Automated Elements 



BOOST 
CONVERTER 




REDUNDANT 
BATTERIES 



I 



REDUNDANT 

BAHERY 

CHARGERS 



UNREGULATED 



AUTOMATIC 

CHARGE 

TERMINATION 



USER LOADS 



INDIVIDUALLY 
FUSED 



rTTTT 



DC POV\€R 



REDUNDANT BOOST 
REGULATOR AND 
INVERTER CHAINS 


REGULATED 


AC AND DC POWER 
DISTRIBUTION 


AC POWER 


AUTOMATIC FAULT 
DtltCTION AND 
POWER CHAIN 
SWITCHOVER 







Candidate Functions for Automation 



Function 



BATTERY CHARGE CONTROL 



POWER CHAIN FAULT DETECTION 
AND SWITCHOVER WITH CROSS 
STRAPPING 



SUBASSEMBLY PERFORMANCE 
MONITORING 



SUBASSEMBLY FAULT DETECTION 
AND RECOVERY 



Description 



• AUTONOMOUSLY BEGIN CHARGING WHEN SOC FELL 
BELOW A PREDETERMINED LIMIT 

• SWITCH TO LOW RATE WHEN SOC REACHED A 
PREDETERMINED LIMIT 

• PREDETERMINED LIMITS VARIED ACCORDING TO 
TEMPERATURE MODEL 



• MAIN AND STANDBY BOOSTER REGULATORS CROSS 
STRAPPED TO MAIN AND STANDBY INVERTERS 
ALLOWING ANY PERMUTATION OF INVERTERS AND 
BOOST REGULATORS UPON DETECTION OF A FAULT 



• EFFICIENCIES CALCULATED VIA INPUT AND OUT- 
PUT VOLTAGES AND CURRENTS FOR POWER 
DEVICES SUCH AS INVERTERS, CHARGERS, ETC. 

• CELL MONITORING WITHIN BATTERIES 



• DETECTION THROUGH CALCULATION OF REDUCED 
EFFICIENCY 

• RECOVERY THROUGH SUBASSEMBLY REPLACEMENT 
(BLOCK REDUNDANT) 



o 



Candidate Functions for Automation (cont) 



Function 



Description 



POWER MARGIN MANAGEMENT 



LOAD EQUIPMENT MONITORING 
AND FAULT DETECTION 



•SHARE MODE DETECTION AND BOOST CONVERTOR 
TIME-OUT LEADING TO LOAD SHEDDING 

• MONITOR LOAD VOLTAGES AND CURRENTS TO 
DETERMINE IMPEDANCE OF LOAD DEVICES 

• IF IMPEDANCE FELL BELOW PREDETERMINED LIMIT, 
DEVICE WAS REMOVED 



RELAY STATUS MONITORING 



• MONITORED POSITIONS OF ALL RELAY CONTACTS 
INCLUDING RELAYS FOR CELL BYPASS, CROSS 
STRAPPING, LOAD DISTRIBUTION, ETC. 



DATA ACQUISITION, PROCESSING, • SERIAL DATA BIT STREAM - RECONFI CURABLE 



AND STORAGE 



DATA STORAGE FOR COMPUTATION 



MINIMUM SOLAR ARRAY MARGIN •PROGRAMMABLE, PRIORITIZED, SEQUENTIAL 
PROTECTION LOAD SHEDDING IF SOLAR ARRAY MARGIN FELL 

BELOW A SELECTED VALUE 



SUBSYSTEM PERFORMANCE 
MONITORING 



DETERMINE THE HEALTH (EFFICIENCY) OF THE 
POWER SUBSYSTEM BY COMPUTING THE INTERNAL 
POWER LOSSES (TOTAL SOURCE POWER INPUT 
MINUS THE TOTAL LOAD POWER DELIVERED) 



Candidate Functions for Automation (cont) 



FUNCTION 



LOAD PROFILE DETERMINATION 



LOAD SEQUENCE GENERATION 



DESCRIPTION 



UTILIZING A PRE-PROGRAA/IIViED OR GROUND 
GENERATED SEQUENCE OF SPACECRAFT COMMANDS, 
CALCULATE THE MAXIMUM POWER AND ENERGY 
STORAGE REQUIREMENT FOR THE SEQUENCE AND 
COMPARE TO THE SOLAR ARRAY AND BATTERY 
SOURCES CAPABILITY. SEND AN ALARM FLAG 
TO THE FLIGHT DATA SYSTEM FOR TRANSMIHAL 
TO GROUND. IF SOURCE CAPABILITY IS LESS 
THAN REQUIRED. 



•UTILIZING THE PRIORITIZED SEQUENTIAL LOAD 
SHEDDING DATA, GENERATE A NEW LOAD SEQUENCE 
BASED ON POWER SOURCE CAPABILITY 



o 

00 



o 



implementation Decisions 
Candidate Functions For Automation 

Function Rationale 



BATERY CHARGE CONTROL 

POWER CHAIN FAULT DETECTION AND 

SWITCHOVER WITH CROSS STRAPPING 

SUBASSEMBLY PERFORMANCE MONITORING 

SUBASSEMBLY FAULT DETECTION AND RECOVERY 
POWER MARG I N MANAGEMENT 

LOAD EQUIPMENT MONITORING AND FAULT 
DETECTION 

DATA ACQUISITION, PROCESSING, AND 
STORAGE 

RELAY STATUS MONITORING 



} 



DEMONSTRATE REDUCED MONITORING 
REQUIREMENTS 

DEMONSTRATE INCREASED FAULT TOLERANCE 
AND FLEXIBILITY 

DEMONSTRATE INCREASED FAULT 
TOLERANCE, FLEXIBILITY, AND 
RECONFIGURABILITY 

DEMONSTRATE POTENTIAL FOR REDUCED POWER 
SOURCE MARGIN 

DEMONSTRATE INCREASED FAULT TOLERANCE 
FLEXIBILITY, AND RECONFIGURABILITY 

DEMONSTRATE MORE FLEXIBLE, RECONFIGUR- 
ABLE TELEMETRY INTERFACE 

DEMONSTRATE REDUCED TELEMETRY REQUIREMENT 



MINIMUM SOLAR ARRAY AAARGIN PROTECTION 
SUBSYSTEM PERFORMANCE MONITORING 
LOAD PROFILE DETERMINATION 
LOAD SEQUENCE GENERATION 



MAXIMUM POWER POINT DETECTOR REQUIRED 



COMPLEX, DOABLE SOFTWARE TASK 



VO 75 Power Subsystem 
APSM Configuration 



BOOST 
CONVERTER 



SOLAR 
ARRAY 



REDUNDANT 
BATTERIES 



REDUNDANT 

BATTERY 

CHARGERS 



UNREGULATED 



DC POV\tR 



REDUNDANT BOOST 
REGULATOR AND 
INVERTER CHAINS 



AC POWER 



USER LOADS 



t t t t t 



REGULATED^ AC AND DC POWER 



DISTRIBUTION 



• BATTERY CHARGE CONTROL 

• FAULT DETECTION & RECOVERY 

• PERFORMANCE MON ITOR ING 



LOCAL PROCESSOR 



• FAULT DETECTION AND 
SWITCHOVER OF ELEMENTS 

• PERFORMANCE MONITORING 



o 

en 



LOCAL PROCESSOR 

I 



I 



LOAD MONITORING AND 
FAULT DETECTION 

• REUY STATUS MONITORING 



LOCAL PROCESSOR 



POWER MARGIN MANAGEMENT 
•SERIAL BIT STREAM TELEMETRY 



CENTRAL PROCESSOR 



o 
en 



APSM Evaluation Results 



Function 



BATTERY CHARGE CO^JTROL 



Test 

• STATE OF CHARGE 
ESTIMATOR EVALUATION 

• BAHERY OVER-TEMPERA- 
TURE SIMULATION 

• BATTERY STATE OF CHARGE 
RESPONSE TEST 

•BAHERY DISCHARGED 



Results 

• WITHIN ±10% OVER 3 CHARGE/ 
DISCHARGE CYCLES 

•CHARGER SWITCHED TO LOW RATE 



•CHARGER SWITCHED TO HIGH 
RATE 



POWER CHAIN FAULT -MAIN INVERTER FAILURE 

DETECTION AND SWITCHOVER S IMULATION 

•MAIN BOOSTER REGULATOR 
FAILURE SIMULATION 



BATTERY OVERCHARGED •CHARGER SWITCHED TO LOW RATE 

•SWITCHED TO STANDBY INVERTER 



•SWITCHED TO STANDBY BOOSTER 
REGULATOR 



SUBASSEMBLY PERFORM- 
ANCE MONITORING 



•CALCULATE EFFICIENCIES OF 
SUBASSEMBLIES AND COM- 
PARE TO RESULTS OF HAND 
CALCULATIONS 



•RESULTS WITHIN 5% 



o 



Function 



APSM Evaluation Results (cent) 

Test Results 



SUBASSEMBLY FAULT 
DETECTION AND RECOVERY 



• BATTERY CHARGER 
EFFICIENCY BELOW LIMIT 
SIMULATION 

• BAHERY CELL VOLTAGE 
BELOW LIMIT SIMULATION 



• CHARGER TURNED OFF 



• FAILED CELL BYPASSED AND 
SPARE CELL CONNECTED 



POWER MARGIN MANAGE- 
MENT 



TOTAL LOAD SIMULATED •SEQUENTIAL LOAD SHEDDING 
TO BE IN EXCESS OF SOLAR SEQUENCE EXECUTED 
ARRAY CAPABILITY 



LOAD EQUIPMENT MONITOR- 
ING AND FAULT DETECTION 



• SIMULATED VARIOUS LOAD •ACCURATELY DETECTED AND 
FAULTS D I SCONNECTED FA I LED LOAD 

•CALCULATED EACH LOAD •CALCULATIONS WITHIN ±2% 
IMPEDANCE AND COMPARED 
TO RESULTS OF HAND 
CALCULATIONS 



RELAY STATUS MONITORING 



►TESTED BY EXECUTION OF •ACCURATE MAINTENANCE OF 
SEQUENTIAL RELAY EXC ITA- RELAY STATUS DATA 
TION COMMANDS 



DATA ACQUISITION, 
PROCESSING AND STORAGE 



'COMPARE HARDWIRE 
MEASUREMENTS WITH 
APSM DATA 



•ACCURACY OF APSM DATA WITHIN 
MEASUREMENT TOLERANCES 



o 

00 



APSAA Results 



TECHNICAL 



PROGRAMMATIC 



APSM Technical Results 



• ACCOMPLISHED OBJECTIVES OF DEMONSTRATING THE AUTOMATION OF 
KEY FUNCTIONS IN POWER SUBSYSTEM 

•CONTINUOUS MONITORING NOT REQUIRED 

• ALGORITHMS FOR KEY FUNCTIONS SUCH AS LOAD MANAGEMENT, 
SUBSYSTEM FAULT TOLERANCE 

•HIGHLIGHTED IMPORTANCE OF SYSTEM CONSIDERATIONS SUCH AS 
INTERFACE MANAGEMENT 

•NEW INVENTIONS NOT NECESSARY TO ACCOMPLISH OBJECTIVES 

• APSM ACTIVITY HIGHLIGHTED FUNCTIONS THAT WOULD BENEFIT FROM 
ADVANCED TECHNOLOGY 

•ACCURATE STATE OF CHARGE INDICATOR 

• SELF-TEST OF STANDBY UNITS 
•MAXIMUM POWER POINT DETECTOR 

• MODULARITY 



o 



APSM Technical Results (Cont) 



•AUTOMATION COULD BE SUCCESSFULLY ACCOMPLISHED WELL WITHIN 
STATI OF THE ART OF ONBOARD COMPUTATIONAL CAPABILITY 

•USE OF ONBOARD COMPUTATIONAL CAPABILITY CAN HAVE POSITIVE 
EFFECT ON POWER SUBSYSTEM CHARACTCRISTICS 

SPECIFIC POWER 50% INCREASE WHEN COUPLED WITH 

ADVANCED TECHNOLOGY 

PRELAUNCH COST SLIGHT REDUCTION - SINGLE SPACECRAFT 

40% REDUCTION - FIVE SPACECRAFT 

OPERATIONS COST 50% REDUCTION 

FAULT TOLERANCE IMPROVED THROUGH PERFORMANCE 

MONITORING 

FLEXIBILITY INCREASED WITH RECONFIGURABILITY 



APSAA Programmatic Results 



• MORE COMPLEX TASK THAN ORIGINALLY ANTICIPATED 



• IMPORTANCE OF CORRECT MIX OF POWER SYSTEM 
ENGINEERS, SOFTWARE EXPERTS, AUTOMATION EXPERTS 

•"SYSTEMS" VIEWPOINT ESSENTIAL FOR MAXIMUM BENEFIT 
•DISTRIBUTED vs CENTRALIZED 
• REDUNDANCY MANAGEMENT 
•DEGREE OF MODULARITY 

•NEED FOR MANAGEMENT OF SOFTWARE DESIGN 



ro 



Future Planetary Spacecraft 
Power System Requirements 



CONSIDERATIONS 



SPECIFIC POWER 



DEGREE OF AUTONOMY 



RELIABILITY 



INTERDEPENDENCE OF POWER/SPACECRAFT DESIGN 



DISTRIBUTION OF COMPUTATIONAL CAPABILITY 



MISSION DURATION 



ROUND TRIP LIGHT TIME 



POWER SYSTEM COST 



Advanced Planetary Power System 
Requirements 



FAULT 
TOLERANCE 





LONG 
LIFE 



SPACECRAFT 
REQUIREMENTS 




u 



POWER SYSTEM \ 
REQUIREMENTS I 



AUTOMATION 




POWER SYSTEM REQUIREMENTS ARE INTERACTIVE WITH 
MISSION AND SPACECRAFT DESIGN 



Typical Power System Mass 





POWER 
KW 






MASS. KG 










SCIENCE 
PAYLOAD 


SPACE- 
CRAFT 


POWER 
El FCT 


POWER 
SYSTEM 


pwr/sc 


pwr/payloap 


VIKING ORBITER 


0.6 


73 


25^0 


37 


178 


7 


2^0 


VOYAGER 


0.^8 


108 


792 


25 


137 


17 


130 


GALILEO 


0.6 


98 


2078 


30 


w 


7 


150 


NEP (Neptune) 
Orbiter 


100 


150 


17000 


685 


3990 


2^ 


2660 


SEP (Halley) 


25 


m 


2082 


312 


1112 


53 


900 



High Power Systems need growth from ^ W/KG to 25 W/KG 
Advanced Power System R & D has large potential payoff! 



Future Requirements 
Advanced Planetary Power Systems 



DRIVERS 



LOW POWER SYSTEMS (0.4-1 kw) 

LOW COST DESIGNS - HIGH INHERITANCE 

LONG LIFE 

REDUCED MISSION OPERATIONS 

REDUCED SYSTEM MASS 

FAULT TOLERANCE 

HIGH POWER SYSTEMS (10 - 1000 kw) 

REDUCED SYSTEM MASS 

FAULT TOLERANCE 

LONG LIFE 

REDUCED MISSION OPERATIONS 

LOW COST DESIGNS 



System-Level Issues in Advanced 
Autonomous Planetary Power Systems 



1. DEGREE OF POWER SYSTEM AUTONOMY REQUIRED 



2. DISTRIBUTION OF ON-BOARD PROCESSING AND CONTROL FUNCTIONS 



3. EFFECT OF POWER SYSTEM AUTONOMATION ON USER SYSTEM REQUIREMENTS 



4. EVALUATION OF BENEFITS OF FLEXIBILITY AND MARGIN CONTROLS 



5. IMPACT OF POWER SYSTEM AUTONOMY ON SPACECRAFT DES IGN 



6. DEFINITION OF DIGITAL DATA AND CONTROL INTERFACES 



Technical Issues in Advanced 
Autonomous Planetary Power Systems 



1. COST/ BENEF IT UNCERTA INTY FROM POWER SYSTEM AUTONOMY 
MASS/ COMPLEXITY/ COST 



2. DEFINITION OF POWER SYSTEM AUTONOMY STRATEGIES WHICH 
DO NOT IMPACT RELIABILITY 



3. DISTRIBUTION OF POWER SYSTEM AUTONOMY BETWEEN DIGITAL 
AND ANALOG FUNCTIONS 



4. INFLUENCE OF POWER SYSTEM CHARACTERISTICS ON AUTONOMATION 
STRATEGIES (AC VERSUS DC, etc.) 



00 



Recommended Planetary Power System 
Automation Objectives 



1. IDENTIFICATION OF POWER SYSTEM FUNCTIONS WHOSE AUTOMATION HAS 
HIGHEST PAYOFFS (MASS/COMPLEXITY/COST) 

2. DEVELOPMENT OF A METHODOLOGY FOR EVALUATING BENEFIT OF AUTOMATING 
SPECIFIC POWER SYSTEM FUNCTIONS 

3. DEVELOPMENT OF CRITERIA FOR DISTRIBUTING DATA AND CONTROL FUNCTIONS 

• GROUND VERSUS ON-BOARD 

• ON-BOARD CENTRAL VS. DISTRIBUTED 

4. ASSESSMENT OF INTERACTION OF AUTOMATION STRATEGIES WITH POWER SYSTEM 
CHARACTERISTICS 

• AC/DC DISTRIBUTION 

• VOLTAGE LEVEL 

t DIGITAL/ANALOG LOGIC 

5. IDENTIFY POWER HARDWARE DEVELOPMENTS REQUIRED FOR AUTOMATION 



iVlARTIN MARIETTA POWER SYSTEM AUTOMATION EXPERIENCE 



o 



AUTOMATED POWER SYSTEMS CONTRACTS AND REU\TED I R&D PROJECTS 



Title 

Flexible Charge 
Discharge Controller 
(FCDC) 



Customer 
or I R&D 

D61D 
I R&D 



Period of 
Performance 

1975-1976 



Single-Cell Protector 
(SCP) 



NASA 
LeRC 



1975-1976 



Description of Effort 

- Single-Cell Protection and Cell 
Bypass 

- A-h Integration Charge Control 

- Uses Intel 8080 Microprocessor 

- Breadboard System Controlling 
Thirty 8 A-h NICd Cells 

- Monitor Single-Cell Voltage and 
Ceil Bypass 

- Analog and Digital Logic 
Implementation 

- Prototype System Demonstrated 
on Single 40 A-h Cell in 
Life-Cycle Test 



AUTOMATED POWER SYSTEMS CONTRACTS AND RELATED I R&D PROJECTS (cont) 



Title 

Multiplexed Cell 
Protector (MCP) 


Customer 
or IR&D 

NASA 


Period of 
Performance 

1976 


Description of Effort 

- Same as SCP with Following 
Differences: 

MCP Multiplexes 18-Cell Battery 
Prototype System Demonstrated 
with 18-Cell Battery 



no 



AUTO/VIATED POWER SYSTEM AAANAGEMENT (APSM) 



Sponsoring Agency: Jet Propulsion Laboratory 

Contract Phases: 

- Configuration Study 

- Hardware Contract 

Period of Performance: 1977-1979 

Contract Description: 

- System H/W Design 

- System S/W Design 
System Conceptual Design 

- Integrate Design H/W and S/W with Viking Orbiter 75 Government-Furnished H/W 



LINEAR CHARGE CURRENT CONTROL (LC^) 



Project Support: 

- Air Force Supported Part of Effort 

- I nternal I R&D Project Supported Another Part of Effort 

Period of Performance: 1976-1980 



Objective: 

- Long Life, High Reliability 

- High Level of Load Management 

- Lighter Weight and Lower Volume 



Implementation Feature 

- Special NiCd Charge Control Algorithm 

- Individual Cell Monitor 

- Accurate State of Charge Monitor 
and Telemetry 

- Unique Power H/W Approach That 
Does Not Use Switching Regulators 



OJ 



4^ 



POWER SYSTEM GOALS UTILIZING DISTRIBUTED MICROPROCESSOR APPROACH 



Spacecraft Computer 
Commands 
Data 

Monitoring 
Diagnosis 
Cabling 



Unified Data 
System Bus 



GSE 
Reduce GSE 
Acceptance Tests 




Local 
Microprocessor 



Local 
Microprocessor 



Power System 
Subassembly 1 



Powpr System 
Subassembly N 



Battery 

Cycle Life 

Weight 

Reliability 
Power Conditioning Equipment 

Efficiency 

Weight 

Flexibility 
Solar Array 

Size 

Weight 



Functional Capability 



3 
The LC !s a Flexible Battery Charge Control System 



Battery Temperature Control 



Battery Temperature Compensated Voltage Control 



Ampere-Hour Integration 



Caution and Shutdown 



!S3 
C7T 






Electrical Capability 



The electrical capability listed is for the breadboard system. The basic design 
is not limited to these levels. 



Output Voltage: 20to40Vdc 



Input Voltage: 20to42Vdc 



Output Current: to 40 A 



Efficiency: 96. 7 to 97. 1% Maximum Load 



EPS MOCKIJP FUNCTIONAL DIAGRAM 



SOIAR A»RAY BUS 



Sii'iiilalor 
Uppei 
Seg me nl 
1 



■jolii r 
Array 
Simulator 
I oive r 
Sct nte nl 
I 



^1 



Solar 
Array 
Si»'ilalor 

llpp e r 
Scg nie nt 
n 



Solar 
IVrray 
Siinirlalor 
Loiver 
Sey nie nt 



Sequent- 
ial 

Partial 
Shunt 
Array 
Regulator 



li 



linear 

Current 

Regulator 



Linear 
Current 
Rcu Ilia tor 



Battery Seii Sing "*^\^ 

• Cell Voltage </ 
t Battery Voltage 

• Battery Temperature 
( Battery Current 



b 



•"giitery 
! Regulator 
j (.tegutated 

Model 



-»• Ifc 

lUnregulated 

Model 



rSiHery J 

Regulator ■ 

* IRegulated f" 



^V)de) 



4 mooe I ; 



lUnregulated 
Model 




load Banic 



ii 



-., 



SyMemlntertace (Control) Unit 
Mkronrocessor/Microcoinputer Interface 



T 



ix'crrial 

Da!<>' fiiiiiinand tinlV' 



OHiicateil Battery ~ 

Mananenienl Microprocessors 



ExiMnal 

Data; Lomina nd link jr- 



I'ofjer ManjH""fi'>l Microcomputer 
S t'eripherals 



t- 



SYSlemMocliup les ls: 

• EPS Power Managenient 

• Battery Charge Control 

« EPS energy Balance Control 

• EPS fault Protec lion 
» Corrective Actions 



CO 



POWER HARDWARE ADVANTAGES 



Size and Weight Reduction: 

- No Switching Regulators 

- No Large Magnetics 

Efficiency: 

- No Switching Regulator Losses 

- Dissipation Reduced by a Factor of 2 to 3 

- Solar Array Size Reduction 

EMC: 

- Switching Regulators are a Prime Noise Source 

- Noise is Reduced Considerably 



PROGRAMAAABLE POWER PROCESSOR (P^) 



NASA MSEC Objective: 

- Design, Build, and Test P^ 

I R&D Project Objective: 

- Perform Qualification Testing on P^ 

Period of Performance: Nov 1979-Nov 1981 



Objective: 

- Reduce Development Cost 

- Usable on Several S/C 

- Develop Mechanical Design, and 
Build Engineering Model 

- Minimize Size and Weight 

- Perform Preliminary Qualification 
Test 



implementation Feature 

- P^ Design Can Be Used for Several Functions 

- No H/W Changes Other Than ROM Change 
Required to Change from One Mode to Another 

- Flexible Interface Command and Data Interface 



PO 



o 



P^ Functional Capability 



3 
A single P component can operate in several different modes. 

- Battery Control 

- Battery Charger 

- Peak Power Tracker (Solar Array) 

- Caution and Shutdown 

- Bus Voltage Control 

- Voltage Regulator 

- Caution and Shutdown 

- Power Li miter (Shuttle Power Extension Package) 

- Peak Power Tracker 

- Fuel Cell Current LImiter 

- Caution and Shutdown 

- Power Bus Over Voltage Protection 

- Shunt Regulator 

- Caution and Shutdown 



Requirements 



Input 

Voltage: 25 Vdg to 375 Vdc 

Voltage ^50 Volts for 20 ms 
Transient 

Power: Less Than 20 Kw 

Inrush: 25 Joules Above Normal Load 

Ripple: 5.0 Amps rms 



00 



Requirements 



Output 



Voltage: 

Degraded 
Performance: 

Current: 
DC Power: 



24Vdctol80Vdc 

0to24Vdc 
to 100 Adc 

Input Voltage 
150 Vde 
250 Vde 
200 Vdc 



Output Voltage 
30 Vdc 
150 Vdc 
150 Vdc 



Output Current 
90 Adc 
40 Adc 
80 Adc 



The above steady levels are required for base plate temperatures of less than 30^0. 
1.1% XV, 



Ripple: 




Ripple Voltage, Volts RMS 
.5%xVq 



30 Hz 50 KHz 

1. 5 KHz 



P^ Simplified Biocic Diagram 



Bias 
Regulator 



FMDM or 
RiU l/F 



Power Stage 



"\_/ 



-rvYW. 






il <, ,1 



Power Base Drive 



JM 



Pulse Width Modulator (PWM) 



a ,; 



p2 Control 



n M II 



WW^ 



LS 



Processor 



' " ' 



Internal 
I/O 



a M M 



^^ Output 
Power 



PROM 



PC/I 



I Patch 1_ P^ Programmable Power Processor 
To RIU or FMDM T ^'"9 I p2 Rower Processor 

PC/I Programmable Controller and Interface 



CO 



GO 

-P=. 



MINIATURE AUTOMATED POWER SYSTEM (JVIAPS) 



Period of Performance: A/lay 1982 

System Description: 

- Totally Automated Terrestrial Battery Charger 

- Two Series 6 A-h NiCd Cells 

- Solar Array Power Source 

- RCA 1802 Microprocessor 

- 1-k, 8-bit CMOS ROM 

- One Hundred Twenty-Eight 8-bit CMOS RAM 

- Monitoring Each Cell, If Cell Is Bad, Replace with One of Four Spare Cells 

- Power Supply Operates Down to 0. 5 V, Voltage 

Status: 

- Breadboard Build and Test Complete 

- Packaging Design to Be Initiated Soon 



TECHNOLOGY ISSUES 



1) Developing Entire Power Systems, Power System Submodules, and/or Lower Level 
Components 

2) Approach to Requirement Definition for Advanced Power System Development 

3) S/C Power System Control Partitioning in Areas of Load Management, Fault 
Detection, and Corrective Action 

4) S/C and Subsystem Control H/W and S/W Architecture 

5) Control Methods and Resulting Algorithms for New Components, such as NIH^ 
Batteries, and for New Annlications, such as Shuttle PEP Power Li miter 



OJ 



SPACE POWER SYSTEM AUTOMATION WORKSHOP 
28/29 OCTOBER 1981 
MARSHALL SPACE FLIGHT CENTER 






Dave Massie 
AFWAL/POOC 
WPAFB, OH 45433 
513-255-6235 



CO 
03 



DEVELOPMENT HISTORY - SUPPORTING TECHNOLOGY 



HIGH VOLTAGE HIGH POWER SYSTEM 

O ADVANCED SILICON AND GALLIUM AR- 
SENIDE SOL^R CELLS 

O NICKEL-HYDROGEN BATTERY TECH. 

HIGH ENERGY DENSITY RECHARGEABLE 
BATTERY TECHNOLOGY 

HIGH EFFICIENCY MULTIPLE BANDGAP 
CASCADE CELL TECHNOLOGY 

CONCENTRATING PHOTOVOLTAIC POIVER 
SYSTEMS TECHNOLOGY DEVEL, 

PRIMARY FUEL CELL TECHNOLO9Y 

REGENERATIVE FUEL CELL TECHNOLOGY 

NUCLEAR RADIATION HARDENING TECH, 

LASER RADIATION HARDENING TECH. 

LIGHTWEIGHT SOLAR ARRAY TECHNOLOGY 
FRUSA, HASPS 



O MEGAWATT TURBOALTERNATOR TECH. 

O PM GENERATOR TECH. 

HIGH POWER SWITCH TECHNOLOGY 

ADVANCED POWER PROCESSOR TECH. 

SC INDUCTIVE ENERGY STORAGE TECH, 



AUTOMATION OBJECTIVE 



AUTOMATIC REAL TIME MONITORING OF EPS HEALTH, COMPUTATION, AND 
COMMAND/CONTROL OF SPACE VEHICLE POWER FROM SOURCE TO LOADS 
BASED UPON SENSING 

o TEMPERATURES 

o PRESSURES 

o CURRENTS 

o VOLTAGES 

o ANGULAR POSITIONS 

o ACCELERATION 

o DISPLACEMENTS 



CO 



4i> 
O 



BENEFITS OF POWER SYSTEM AUTOMATION 

IMPROVED RELIABILITY/SURVIVABILITY 

SIMPLIFIED GROUND STATION COMMAND AND CONTROL FUNCTIONS 
RELATED TO SPACE VEHICLE ELECTRICAL POWER SYSTEMS OPERA- 
TIONS 

REAL TIME ELECTICAL POWER SYSTEM STATUS AND CONTROL 

QUICK RESPONSE TO CHANGING POWER NEEDS AND NEEDS FOR SELF- 
PROTECTION - VIRTUALLY NO TIME DELAY BETWEEN SENSING ANOMALOUS 
OPERATION AND EPS "SAFING" 

O LOWER WEIGHT AND COST (PARTICULARLY IN THE ESS) 



AUTOMATED POWER SYSTEM GENERAL FUNCTIONS 



POWER MANAGEMENT 



O LOAD MANAGEMENT 



O RELIABILITY MANAGEMENT 



CONFIGURATION MANAGEMENT 






AUTOMATED POWER SYSTEM SPECIFIC FUNCTIONS 



O BATTERY CHARGE /DISCHARGE CONTROL, PROTECTION AND RECONDITIONING 

O POWER SOURCE CONTROL AND VOLTAGE REGULATION 

FAULT DETECTION, ISOLATION, AND AUTOMATIC CORRECTION/COMPENSATION/RE- 
CONFIGURATION 

O EPS HEALTH AND STATUS MONITORING 

O EPS DATA PROCESSING, DATA STORAGE AND RETRIEVAL 

O SOLAR ARRAY ORIENTATION CONTROL 



ISSUES 



O FAILURE TO INCORPORATE AUTOMATIC DETECTION OF EPS FAULTS 
WITH SUBSEQUENT ON-BOARD CORRECTION/RECONFIGURATION WILL 
RESULT IN CONTINUED INCREASE IN RELIANCE ON GROUND STATION 
COMMAND/CONTROL/DATA PROCESSING 

O STATION COMMAND AND CONTROL FUNCTIONS VERSUS AUTOMATED COM- 
MAND AND CONTROL FUNCTIONS 

ABILITY TO PREDICT POWER SYSTEM PERFORMANCE PARAMETERS FOR 
THE LIFETIME OF THE SPACE VEHICLE 

O NEED FOR CONTINUED OPERATION OF MILITARY SPACE VEHICLES WITHOUT 
GROUND STATION COMMAND/CONTROL 

O DEVELOPMENT OF STATUS MONITORING/SENSING CIRCUITRY AND CONTROL 
ALGORITHMS 



CO 



TASK 682J10 - FAULT TOLERANT POWER SYSTEM 
Section I Requirement 

a. Background - Program Genesis and Motivation 

Satisfactory operation of military satellites is dependent upon 
an adequate and reliable source of electrical power. Over the years 
solar array/battery power systems have operated to a significant degree 
under the command/control capabilities of satellite tracking stations 
which periodically monitor the health of the system. With the advent 
of advanced microprocessor and computer technology is is now feasible 
to provide an autonomous electrical power system management capability. 
Such a capability would greatly relieve and simplify ground station 
command and control functions related to satellite electrical power 
system operations. 

Satellites are not always in communication with ground 
stations. Therefore, in the event of a power system anomaly, the 
capability to autonomously sense the anomaly and reconfigure the 
operation of the power system would enhance the reliability of the 
system. The key to achieving this capability is to place each element 
of the power system under the control of a dedicated local microprocessor/ 
microcomputer as illustrated in Figure 1. This approach would permit 
power system capability to perform automatic real time monitoring of 
health, computation, and command/control of spacecraft power from source 
to loads. Virtually no time delay would be encountered in sensing and 
"safing" electrical power system operations in the event of malfunctions 
thus avoiding severe system degradations which might otherwise occur. 
The automatic fault detection and correction capability could also 
significantly enhance the survivability of the spacecraft power system. 



144 



















































— ► 
— ► 

V 












Solar 
Array 

(Simulator) 




i 








I ' 


Load 
Distributor 


EPS 

Loads 

(Simulator) 




-- 


Charger 


Battery 




Battery 
Regulator 




r" 







1 

1 


Local 
Microprocessor 


Local 
Microprocessor 


Local 
Microprocessor 


Local 
Microprocessor 


Local 
Microprocessor 


Local 
Microprocessor 


1 


-• 


-- 


' 


-- 








1 





L 


r 





. 


' 





-V- 


' ■ 


— 


■ 

















1 


\ 






















^ System Control 

Interface 








i 




Dedicated EPS 
Microcomputer 
(Intel 8080) 




k 






' 


r 












Ground Control 
Central Computer 




























and/c 
Comr 


r 
na 


nd Si 


TIU 


lator 



























Figure 1 - Fault Tolerant Power System Schematic 



145 



b. Objective - Improvements Anticipated 

The objective of this new task is to demonstrate a Fault 
Tolerant Power System for military space vehicle applications. Ability 
to autonomously diagnose, detect, and correct faults are principal 
features of the system. As such the system would possess inherent 
capability to operate independent of external command/control normally 
provided by satellite ground tracking stations. Ground station command/ 
control involvement would only be required in the event that a system 
anomaly results in an alarm situation where parameters being automati- 
cally monitored exceed pre-established maximum or minimum limits. For 
any anomalous situations short of alarm situations, automatic on-board 
reconfiguration/correction would be implemented with a subsequent report 
to ground stations. Improvements resulting from a Fault Tolerant Power 
System Concept include: 

Autonomy 

Survivability 

Improved Reliability 

Real Time Electrical Power System Status 

Lower Cost and Weight 

Design Simplicity and Flexibility 
The Fault Tolerant Power System (FTPS) will be able to quickly 
respond to changing mission power needs and needs for electrical power 
system self protective measures. Examples include (a) load matching to 
power system capability such as switching off non-essential loads under 
conditions of low bus voltage or supplementing solar array power with 
battery power, (b) automatic disconnect of defective loads, and (c) 
switching out defective battery cells and switching in good spare cells. 
The ability to utilize spare battery cejils as opposed to use of redundant 



146 



batteries provides a tremendous weight savings in the electrical power 
system - doubling or perhaps tripling effective energy density of the 
energy storage subsystem in the FTPS approach may be possible. 

c. Potential Applications 

Technology derived from the FTPS ADP will be applicable to a 
wide range of future Air Force space vehicles where a high degree of 
autonomy, survivability, and reliability are required. Further satellite 
traffic in earth orbit will escalate substantially in the post 1980 
time period. Consequently, it will become increasingly difficult for 
these stations to keep up with command/control and data processing 
requirements. Automation features such as those provided by the FTPS 
will help to relieve and simplify ground station satellite support 
requirements. The spectrum of mission operations to wnich this techno- 
logy applies include surveillance , communications , meteorology , and 
navigation . 

d. Requirements Document List 

The latest approved technical direction document covering work 
related to this task is Program Management Directive R-S 2133 (9)/PE 
63401 F dated 23 December 1977. It should be pointed out however that 
this task is being proposed as a new initiative for FY81 start. This 
task is responsive to SAMSO/ESD Technology Needs TN-SAMSO-AFAPL-1002- 
70-15, "Solar Cell Power Systems"; TN-SAMSO-AFAPL-1 002-76-20, "High 
Efficiency Spacecraft Power Generation", and TN-ESD-AFAPL/AFCRL-1002- 
.70-01, "Solar Energy Conversion". 
Section II Technical Approach 
a. Technical Approach 

The technical approach encompasses (1) command and control 
design tradeoffs, (2) development of sensing circuitry, signal condition- 



147 



ing circuitry, and associated algorithms, (3) microprocessor/micro- 
computer interface definition, (4) design, fabrication and demonstration 
of a breadboard Fault Tolerant Power System as illustrated in Figure 1 
for ground demonstration, and (c) development of preliminary design 
specifications for fault tolerant systems operating in the load power 
range from 5 to 25 KWg. The FTPS breadboard will be configured to 
perform and demonstrate the following general type functions: 
. Load Management Functions 
. Power Management Functions 
. Reliability Management Functions 
. Configuration Management Functions 
In providing the above type of general functions, the FTPS will demon- 
strate many specific functions. Examples of specific functions are as 
follows: 

Battery Charge/Discharge Protection and Pseconditioning 
Solar Array Orientation Control 
Power Source Control and Voltage Regulation 
Fault Detection, Isolation, and Correction 
Power System Data Storage and Retrieval 
The ground tests of the FTPS breadboard hardware will be geared 
to demonstrating the general and specific functions defined above. 
Results of these tests plus the knowledge gained during the course of 
the FTPS program will be utilized in the preparation of design specifi- 
cations. 

b. Alternative Approaches 

Redundancy at the unit level is a possible alternative approach 
to the FTPS concept, however; standby units would add considerable cost 
and weight. Automatic failure detection and switchover to standby units 



148 



is really a trend toward the FTPS concept anyway. Failure to incorpo- 
rate automatic failure detection and switchover would increase reliance 
on active ground station command/control /data processing rather than 
relieve such reliance. Thus, there are no apparent good alternative 
approaches to the FTPS for providing the requisite high degree of 
autonomy, reliability, and survivability. 
c. Technology Transition 

Results of this task will establish an advanced technology 
base for implementing FTPS concepts into future Air Force space vehicle 
systems. The task will demonstrate the autonomy and flexibility of the 
concept through a complete and thorough ground test program. Specifi- 
cations will be developed from which future systems can be tailored. 
The technology derived from this program will be factored ^into the 
development of the High Voltage High Power System of Task 682J08. 
Section III Development Summary 

a. Proposed contractual and AFAPL supporting efforts under Task 
682J10 are structured for the successful development and laboratory 
demonstration of a Fault Tolerant Power System breadboard model. Test 
data and FTPS specifications will be end items of this advanced develop- 
ment program task. 

The work will not require the development of specialized 
microprocessor microcomputer technology. Instead, commercially available 
microprocessors and a microcomputer will be utilized. Some specialized 
sensing circuitry will have to be developed. An example is an ampere- 
hour integrator circuit for measuring battery state-of-charge. 

A development step outline for the FTPS Task is as follows: 



149 



Development Step/Event Initiation Date Completion Date 

FTPS SOW/RFP Preparation; 1 Oct 1980 1 Feb 1981 

Technical Evaluation of 
Proposals; Contract Prep. 

Power System Performance 1 Feb 1981 1 Aug 1981 

Predictions; Command & 
Control Design Tradeoffs 

Develop Sensing Circuits 1 Jun 1981 30 Oct 1981 

and Algorithms 

Microprocessor/Microcomputer 1 Sep 1981 30 Nov 1981 
Integration 

Breadboard FTPS Ground 1 Feb 1981 1 Mar 1982 

Demonstration Hdw Design (Go/No Go) 

Fabrication of FTPS Ground 1 Mar 1982 30 Sep 1982 
Demonstration Hdw 

FTPS Test & Evaluation 1 Oct 1982 30 Jul 1983 

Final Report & Design 30 Jul 1983 30 Oct 1983 

Specifications 

b. Evaluation Criteria 

Key items effecting development of the breadboard FTPS are (a) 
power system performance predictions, (b) command and control design 
tradeoffs and (c) development of sensing circuits and algorithms. These 
key elements of work will receive priority attention early in the program. 
An Interim Technical Report will be delivered at the twelfth (12th) pro- 
gram month covering results of these key items. 

Design of the breadboard FTPS will proceed in parallel with 
other elements of work culminating in a Critical Design Review upon 
completion of approximately fifteen (15) months of effort. The CDR is 
a Go/No Go decision point in the program. Provided there are no 
insurmountable problems identified as a result of the CDR, the contractor 
will be authorized to proceed with hardware manufacture, integration and 
test. 



150 



c. Schedule 

The overall schedule for the various elements of work to be 
conducted under Task 682J10 is shown in the attached AFSC Form 103 - 
Program Schedule. Total duration of the effort, is approximately 
thirty-six (36) months funded over three fiscal years - FY81 , 82 and 
83. 

d. Progress and Accomplishments 

AFAPL has initiated a literature review pertaining to the 
various tec hnical considerations related to the proposed Fault Tolerant 
Power System. Knowledge resulting from this review will be used to 
improve Task 682J10 planning and preparation of a high quality statement 
of work if this task is approved. 

e. Resources 

1. Financial and Manpower - see summary. 



151 



PROGRAM SCHEDULE 


SYSTEM (Pro;ecO NUMBER paiilf 

Tolerant Power System 


SUBSYSTEM 


TYPE OF SCHEDULE 

Advanced Develooment 


AS OF DATE 

8 Marrh iq7« 


L 
I 

N 
E 


WSWMSSsti^^^^^^^^ 


PRiOR 
SCHED 


FY 19 1 FY 19 |fy is 


19 82 


19 83 


.9 84 


COVPLE 
T:OS 
OATES 


L 

r 

N 

E 


DATES 


CY 1980 


CY IS 81 


MO 


YR 


J 


F 


M 


A 


M 


J 


J 


A 


S 


O 


N 


D 


J 


F 


M 


A 


M 


J 


J 


A 


S 


o 


N 


D 


1 


2 


3 


4 


1 


2 


3 


4 


1 


2 


3 


4 


:tr 


YR 


1 




















































































1 


2 


FTPS TPP Submission 


3 


78 














































































2 


3 




















































































3 


4 


Preliminarv Planninq Complete 


3 


80 














































































4 


S 




















































































5 


6 


FTPS SOW/RFP Preparation 






























1 




















































6 


7 


and Tech. Eval . of Proposals 


















































































7 


8 




















































































8 


9 


Power System Performance Predictions 






































: 












































9 


,0 


■ 


































































T 


itjer 


M 


[e 


:h. 


f^t 


.10 


/'■ 






11 
12 


Command & Control Design Trades 






































_i 




2 
















/ 
























11 
























































M 


/ 


























12 


13 


Develop Sensing Circuits & Algorithms 
















































:j 




A 




























13 


14 




















































































14 


15 


Microprocessor/Microcomputer 


























































.^ 




- 


Cn 


ti 


a 1 


"P 


?ST 


qn 


15 


16 


Integration 
























































y 








^e 


VI 


2V 


"1 


3 


^ 


lo 


Ro' 


16 


17 
























































.Y 


























17 


18 


Breadboard FTPS Ground 




















































A- 




























18 


19 


Demonstration Hdw. Desiqn 


















































































19 


20 




















































































20 


21 


Fabricate FTPS Ground 


















































































21 


22 


Demonstration Hdw. 


















































































22 


23 




















































































23 


24 


FTPS Breadboard Test & Evaluation 






























































t" 


















24 


25 




















































































25 


26 


Final Technical Report & 
































































zv 
















25 


27 


Design Specifications 


















































































27 


28 


■ 


















































































28 


29 




















































































29 


30 




















































































3D 


31 


















































































1 — 


3! 


32 




















































































22 


33 






















































r- 






























33 


34 




















































































34 


35 





















































































35 


36 


















































































36 


AUTHENTICATION ] 


J 


F 


M 


A 


M 


J 


J 


A 


S 





N 


D 


J 


F 


M 


A 


M 


J 


J 


A 


S 


o 


N d] 


\ 


2 


3 


4 


1 


2 


3 4 


1 


2 


3 


4 


1 












' 



PREVIOUS EDITION WILL BE USED. 



Section IV Management Concept 

a. Management Agency 

The AFAPL is responsible for the management of all contractual 
and in-house efforts under this task while SAMSO is responsible for 
management of Program Element 63401 (including 682J - Advanced Space 
Power Supply Technology) funds and the identification of Spacecraft 
power technology needs. 

b. Participating Agencies 

1. Responsibilities 

SAMSO will manage all P.E. 63401 F funds, identify user needs 
and coordinate on all Statements of Work, AF Form 111, DD Form 1634, 
Technical Program Plans and Requests for D&F. The AFAPL will manage all 
Project 682J contracts and in-house efforts, support SAMSO through sub- 
mission of appropriate documentation and participation in briefings and 
studies and will provide the manpower for these activities. 

2. A Memorandum of Agreement between SAMSO, Deputy for Technology 
and the AFAPL covers the work of Project 682J. This MOA and Annex 1 were 
signed in August 1975. 

c. Execution 

1. Execution of the FTPS program will be through an. Advanced Develop- 
ment Contract awarded the successful bidder on a multiple source proc- 
curement. Specific tasks associated with this program are identified 

by Phase in Section II above. 

2. Procurement Approach 

All contemplated procurements will be publicized by synopsis 
in the Commerce Business Daily utilizing the R&D Source Sought procedure. 
A Cost-Plus-Fixed-Fee type contract is presently contemplated based upon 
inability to obtain definitive specifications and lack of previous pricing 



153 



information. Higher risk type contracts will be considered at the time 
of negotiation and will be utilized if practicable, 
3. Program Controls 

The contract resulting from Task 682J10 will require the 
submittal of a Contract Funds Status Report (DD Form 1586), and R&D 
Technical Plan and Monthly Program Schedule and R&D Status Reports. 
Section V Ass essments 

This is a proposed new Space Power Advanced Development program 
for which a priority assessment remains to be made. It is proposed for 
the purpose of significantly enhancing non-nuclear power systems capa- 
bility for future high energy military space vehicle systems using the 
Space Shuttle. 



154 



POWER SYSTEM 
AUTOMATION REQUIREMENTS 
FOR EARTH ORBIT 



J. R. LANIER, JR, 






en 



EPS AUTOMATION QUIZ 



A SYSTEM IS >WHFN IT CAN, TO SOME DEGREE, 

\ SEQUENCE THROUGH A SERIES OF MEASUREMENTS 



OF EQUIPMENT OUTPUTS, COMPARE THESE MEASUREMENTS AGAINST 
STANDARDS, AND TAKE CORRECTIVE ACTION IF THERE IS AN UNACCEPTABLE 
DEVIATION BETWEEN THE MEASUREMENT AND THE STANDARD 



•SUPPLY THE PROPER WORD; "AUTOMATIC" OR "AUTONOMOUS" AND 
"AUTOMATICALLY" OR "AUTONOMOUSLY" AS DESIRFD. 



EPS AUTOMATION DEFINITIONS 



AUTOMATIC: 



(SELF-ACTING) HAVING A SELF-ACTING OR 
SELF REGULATING MECHANISM 



AUTONOMOUS: 



(INDEPENDENT) CARRIED ON WITHOUT OUTSIDE 
CONTROL; EXISTING INDEPENDENTLY. 



AUTOMATION: 



AUTOMATICALLY CONTROLLED OPERATION OF A SYSTEM 
BY MECHANICAL OR ELECTRONIC DEVICES THAT TAKE 
THE PLACE OF HUMAN ORGANS OF OBSERVATION, 
DECISION, AND EFFORT. 






CO 



EARTH ORBITAL POWER SYSTEM AUTOMATION 
REQUIREMENT 



TO PROVIDE CONTROL OF AN EPS, WITHOUT EXTERNAL INTERVENTION, 
TO EFFECT SYSTEM OPERATION EQUIVALENT TO THAT WHICH WOULD BE 
PROVIDED BY A TEAM OF EPS EXPERTS IN CONTROL OF THE SYSTEM. 






EPS AUTOMATION 



A SYSTEM HAS BEEN AUTOMATED WHEN IT CAN INDEPENDENTLY 
SEQUENCE THROUGH A SERIES OF MEASUREMENTS OF EQUIPMENT OUTPUTS, 
COMPARE THESE MEASUREMENTS AGAINST STANDARDS, AND TAKE CORRECTIVE 
ACTION IF THERE IS AN UNACCEPTABLE DEVIATION BETWEEN THE MEASUREMENT 
AND THE STANDARD. 



o 



EPS AUTOMATION REQUIREMENT IMPLIES: 



• INFORMATION AVAILABLE - SENSORS 

• DATA REDUCTION - COMPUTER 
©LOGIC -COMPUTER 

• DECISION IVIAKING - COMPUTER 

•CONTROL- COMPUTER/RECEIVERS (SWITCH^ ETC.) 



POWER MANAGEMENT SYSTEM FUNCTIOfJS 

'DECODE/ISSUE COMMANDS FROM S/C COMPUTFR 

• ACQUIRE/REDUCE EPS DATA 

►TRANSMIT SELECTED DATA TO TELEMETRY SYSTEM 

► TIME/SYNCHRONIZE POWER SYSTEM EVENTS 

► CONTROL EPS OPERATION 

• POWER GENERATION MANAGEMENT 

• ENERGY STORAGE MANAGEMENT 

• biSTRIBUTION SYSTEM MANAGEMENT 

• LOAD MANAGEMENT 

► INTERACT WITH THERMAL SYSTEM 






DRIVERS FOR EARTH ORBITAL POWER SYSTEM 

AUTOAAATION 



©DATA AVAILABILITY 

• GROUND COVERAGE 

• DATA LINKAVAIL^BILITY 

• TELEMETRY SHARING 
©DECISION TIME 

• DATA REDUCTION 

• HUMAN RESPONSE 
• COST 

• TEAMS OF EXPERTS 

• DATA NETWORKS 



SPACE POWER SYSTEM AUTOMATION WORKSHOP 



AMPS PROGRAM STATUS AND OBJECTIVES 



ARTHUR D. SCHOENFELD 



CO 



MARSHALL SPACE FLIGHT CENTER 
HUNTSVILLE, ALABAMA 

1981 OCTOBER 28 






AUTONOMOUS SPACECRAFT MANAGEMENT CONCEPT 

(ASM) 



• AUTONOMOUS MAINTTENANCE- MAINTENANCE AND OPERATIONS 
TASKS PERFORMED ONBOARD WITHOUT GROUND INTERACTIVITY 

• AUTONOMOUS FAULT DETECTION, ISOLATION, AND REMOVAL - 
SAFEGUARD HEALTH OF THE SPACECRAFT 

• AUTONOMOUS RECONFIGURATION OR RECOVERY- FOLLOW 
PROCEDURES FOR REPLACING FAILURES WITH REDUNDANT PARTS 
OR SWITCH TO ALTERNATE MODES 



ASM VERSUS PRESENT APPROACH SUMMARY 



ASM 



PRESENT 



• HANDS-ON ON-OR BIT CHECKOUT 

• SElf PERFORMANCE MONITOR 

• SELF HEALTH MONITOR 

• MORE DIRECT MEASUREMENT OF HEALTH 

- ADDITIONAL SENSORS INDIVIDUALLY 
MONITORED 



• HANDS-ON ON-ORBIT CHECKOUT 

• PERFORMANCE MONITOR VIA TELEMETRY 

• HEALTH MONITOR VIA TELEMETRY 

• INDIRECT MEASUREMENT OF HEALTH 

-LIMITED TELEMETRY LIST 



• DATA ANALYZED AND SWITCHING COM- 
MANDED BY ON-BOARD FAULT MONITOR 

• TREND ANALYSIS POSSIBLE 



• DATA REVIEWED AND SWITCHING 
COMMANDED BY GROUND CREW 

• TRENOANALYSIS PREDICTS FAILURES 



HIERARCHY OF RESPONSE UP TO SAFE HAVEN • SAFE HAVEN MODE 



C3-1 






HIERARCHICAL STATES 




CRITERIA FOR ASM ACCEPTANCE AND APPLICATION 



CT) 



• ESTABLISH NEED 

- ENHANCED MANAGEMENT OF COMPLEX SYSTEMS 
-VULNERABILITY REDUCED 

-LIFE CYCLE COST REDUCED 
-CONVENIENCE INCREASED 

• DEMONSTRATE NEW TECHNOLOGIES 

-SUBSYSTEM ALGORITHMS 

- SPACECRAFT MANAGEMENT STRATEGIES 

• PROVE THE DESIGN CONCEPT 

- SHOW THAT RELIABILITY AND AVAILABILITY 
ARE IMPROVED 

-SIMULATE AND ANALYZE 

• QUANTIFY RISKS AND BENEFITS 



00 



PROGRAM HIGHLIGHTS 



• ESTABLISHED BASELINE DESIGN FOR MODULAR 250 kW ELECTRICAL POWER 
SYSTEM -MULTIPLE POWER SOURCES AND LOAD CENTERS 



• DEVELOPED MANAGEMENT CONCEPT FOR UTILITY TYPE POWER SYSTEM - FULL 
POWER SOURCE UTILIZATION AND ADAPTIVE CONTROL OF LOAD BUSES 



• DEFINED POWER SUBSYSTEM ALGORITHMS 



• DEVELOPED POWER MANAGEMENT SUBSYSTEM ARCHITECTURE- POWER 
SUBSYSTEM PROCESSORS. AND DISTRIBUTED POWER SOURCE AND LOAD 
CENTER PROCESSORS 



PROGRAM HIGHLIGHTS (Continued) 



• SELECTED FLIGHT QUALIFIED MICROPROCESSORS FOR POWER MANAGEMENT 
SUBSYSTEM 



DEFINED DATA BUS NETWORK AND DATA COMMUNICATIONS PROTOCOLS 



• INITIATED SOFTWARE DEVELOPMENT OF KEY POWER SUBSYSTEM ALGORITHMS 
USING HIGH LEVEL LANGUAGE (FORTH) 



• DEVELOPED CONCEPT FOR A TEST BED AND DEMONSTRATION SYSTEM OF AN 
AUTONOMOUSLY MANAGED 250 kW POWER SYSTEM - INITIAL FACILITY OF 
48 kW EXPANDA BLE I N 16 kW I NCREMENTS 



C7> 



CD 



MULTICHANNEL REFERENCE 
ELECTRICAL POWER SYSTEM DESIGN 







SOLAR 


SOLAR 
ARRAY 




ARRAY 
SWITCH- 
ING 






UNIT 



r 



CHANNEL 17 







CHANNEL 1 



POWER 

SOURCE 

CONTROL 



ENERGY 
STORAGE 



LOAD 
CENTER 
1 



LCC 



• • • 

r- 



■^ FUTURE 
-► SATELLITE 
_^ EXPANSION 



LOAD 
CENTER 

LCC ^° 



I I 
I I 



POWER 

SUBSYSTEM 

CONTROL 



rr TIT 



I LOADS 

.X 1 



LOADS 



LCC « LOAD CENTER CONTROL 



GENERATION - CASSEGRAIN CONCENTRATOR SOLAR ARRAY 

ENERGY STORAGE - NICKEL-HYDROGEN BATTERY (160. 150-AH CELLS) 

BATTERY CHARGER - SOLAR ARRAY SWITCHING UNIT 

REGULATION -220 ± 20 VOLTS (BATTERY CHARACTERISTICS) 

POWER TRANSMISSION - DIRECT CURRENT AT SOURCE VOLTAGE 

POWER DISTRIBUTION - DIRECT CURRENT AT SOURCE VOLTAGE 

POWER PROCESSING - AS NEEDED WITHIN EACH PAYLOAD OR LOAD CENTER 

CHANNEL QUANTITY - DEFINED BY BATTERY CAPACITY (17) 

RELIABILITY - FAIL OPERATIONAL, FAIL SAFE 

GRACEFUL CAPACITY DEGRADATION WITH FAILURES 
LIFE - INDEFINITE; REPLACE FAILED UNIT AT NEXT SERVICE OPPORTUNITY 



CENTRAL PROCESSING FUNCTIONS 
POWER SUBSYSTEM RELATED 



• PAYLOAD OPERATION AND MAINTENANCE 
INTER-SUBSYSTEM CONTROLS 

• MONITOR STATE OF HEALTH OF SUBSYSTEM PROCESSORS 

• PAYLOAD FAULT MANAGEMENT 



FAULT ISOLATION AND CONFIGURATION MANAGEMENT OF 
SUBSYSTEM PROCESSORS 



FAULT TOLERANT CENTRAL PROCESSING 



IN3 



AUTONOMOUS MANAGEMENT 
IS THE HEART OF UTILITY SPACECRAFT POWER 



ENERGY STORAGE 



TRANSMISSION 



DISTRIBUTION 




ADAPTABILrTY 
DEPENDABILmr 
FULL UTILIZATION 
EXTENDED LIFE 
REDUCED REDUNDANCY 



BENEFITS FROM AMPS 



REDUCES REDUNDANCY REQUIREMENTS/COSTS 

- ACCOMMODATES WIDESPREAD DEGRA DAT I ON/FA I LURES THROUGH FLEXIBLE 
LOAD MANAGEMEISfT TECHNIQUES 

REDUCES DEVELOPMENT COST THROUGH MANAGEMENT OF COMPLEX MODULARIZED 
SYSTEMS USING LOWER POWER MODULES AND NEAR TERM TECHNOLOGY 

REDUCES RESUPPLY COSTS BY: 

- OPERATING EQUi PMENT TO EXTEND LIFE 

- EARLY DEGRADATION DETECTION AND CORRECTIVE ACTION 

- RESUPPLY PROJECTIONS 

- MISSION ADAPTABILITY 

► REDUCES GROUND STATION OPERATIONAL COSTS 

- REDUCES COMMUNICATION TRAFFIC REQUIREMENTS 

- MINIMIZES GROUND FACILITIES FOR INCREASING 
SATELLITE QUANTITY/COMPLEXITY 

- FEWER PERSONNEL 

- CONTINUING SUPPORT COSTS REDUCED 



— 1 

CO 



-p. 



BENEFITS FROM AMPS 



• IMPROVES DEPENDABILITY AND PERFORMANCE THROUGH 
USE OF EXTENSIVE DIAGNOSTIC DATA 



• .DECREASES ASTRONAUT MONITORING REQUIREMENTS 



OPERATES UTILITY TYPE POWER SYSTEM FOR A WIDE 
VARIETY OF PAYLOAD MISSIONS AND LOADS 



AUTONOMOUS POWER MANAGEMENT APPLICATIONS 



t SPACE PLATFORMS 



• MILITARY SPACECRAFT 



t MANNED SPACE STATION 



• ELECTRIC PROPULSION SPACECRAFT 



en 



CT> 



CONCLUSIONS 



A UTILITY TYPE POWER SYSTEM CONCEPT HAS BEEN DEVELOPED THAT ALLOWS 
LARGE SYSTEM POWER TO BE ATTAINED WITH NEAR TERM TECHNOLOGY 

MODULAR APPROACH REDUCES DEVELOPMENT AND RESUPPLY COSTS AND 
ENABLES INCREMENTAL ASSEMBLY/EXPANSION OF LARGE POWER STATIONS 

UTILITY TYPE POWER SYSTEM VERSATILITY REQUIRES A NEW APPROACH TO 
POWER MANAGEMENT IN SPACE 

AMPS PROVIDES A COST EFFECTIVE APPROACH TO THE REQUIRED POWER 
MANAGEMENT BY: 

- MINIMIZING GROUND STATION SUPPORT 

- IMPROVING EQUIPMENT LIFE 

- REDUCING RESUPPLY COST 

- ACCOMMODATING WIDE VARIETY OF PAYLOAD MISSIONS AND LOADS 

- RECOVERY FROM EQUIPMENT DEGRADATION AND FAILURE 

AMPS POWER MANAGEMENT STRATEGIES ARE A KEY TECHNOLOGY DEVELOPMENT 
FOR LARGE POWER SYSTEMS AND MILITARY SPACECRAF 



■■STRAWMAN" 
TECHNOLOGY I SSUhS 

AND 
SPECIFIC OBJECTIVES 






00 



TECHNOLOGY ISSUES 



o DISTRIBUTED VERSUS CENTRAL CONTROL 

O ALGORITHM MODELING 

o CONTROL REQUIREMENTS 

b CONTROL PHILOSOPHY 



TECHNOLOGY ISSUES 



DISTRIBUTED VERSUS CENTRAL CONTROL 






CENTRAL 



HYBRID 



DISTRIBUTED 





EPS 






i 


i 

y 




INSTR. 
NO. 1 






V^ 


■^ 


■ 



^^ 




s/c . 

COMPUTER 



INSTR, 
NO. N 



TCS 



PWR. S/S 



S/C 
COMPUTER 



ACS 





EPSC 


























PSC 




LCC 



OTHER S/S ^ 
CONTROLLERS 
1 

I 
f 
I 
I 

i 





s/c 

COMPUTER 






















r\ 


THE 


PSC 




LCC 







00 

o 



TECHNOLOGY ISSUES 



•ALGORITHM MODELING 

ACCURATE MODELING/CHARACTERIZATION OF COMPONENTS 

BETTER UNDfcHblANDING OF COMPONENT CHARACTERISTICS AND THE 
EFFECTS OF VARYING PARAMETERS ON THE COMPONENT RELIABILITY, 
EFFICIENCY, AND LIFE MAY BE NEEDED TO PROPERLY DESCRIBE THE 
COMPONENTS EFFECT ON POWER SYSTEM PERFORMANCE. 

PHILOSOPHY OF REDUNDANCY INTERNAL TO THE ALGORITHM 

DUE TO THE FRAGILE NATURE OF SOFTWARE AND THE POTENTIAL 
CONSEQUENCES OF ERROR, A REDUNDANCY PHILOSOPHY MAY BE 
REQUIRED OTHER THAN THAT INVOLVED AT THE SYSTEM LEVEL. 



STANDARDIZATION VS. OPTIMIZATION 

IT IS IMPORTANT TO RECOGNIZE THE OVERALL SYSTEM ECONOMY IN 
TERMS OF SUFFICING VERSUS OPTfMlZING PHILOSOPHY - - - 
A FAMILY OF "STANDARD" ALGORITHMS MAY BE ADEQUATE BUT SHOULD 
BE COMPARED WITH THE POSSIBILITY OF UNIQUE (OPTIMUM) ALGORITHMS 
FOR EACH NEED. 



TECHNOLOGY ISSUES 



• CONTROL REQUIREMENTS 



DEPTH OF MONITORING (PENETRATION) 



DEPENDING ON SYSTEM REDUNDANCY/RECOVERY PHILOSOPHY, THE 
DEPTH OF MONITORING MAY VARY FROM SUBSYSTEM LEVEL DOWN TO 
COMPONENT LEVEL. {BATTERY TO CELL) 



DATA SAMPLING RATE 

SINCE THE LEVEL OF COMPLEXITY AND CONTROL IS DIRECTLY DEPENDENT 
ON THE DATA SAMPLE RATES/VARYING SAMPLE^RATES MAY BE DESIRABLE 
FOR OPTIMUM SYSTEM MANAGEMENT. 



00 



00 



TECHNOLOGY ISSUES 



CONTROL PHILOSOPHY 



POWER DOwiM VS. LIGHT LOAD OPJERATION 



IT MAY BE DESIRABLE TO POWER DOWN PORTIONS OF A SYSTEM FOR LONG 
PERIODS OF "STANDBY" OPERATIONS AS OPPOSED TO OPERATION OF THE 
TOTAL SYSTEM AT A FRACTION OF ITS RATING. 



LOAD SHEDDINu (PRIORITIZATION) 

FOR CERTAIN SITUATIONS IT MAY BE DESIRABLE TO PRIORITIZE LOADS 
(OR LOAD BUSES) AND ENABLE BUSES ACCORDING TO SYSTEM CAPACITY. 



SELF-DIAGNOSIS AND OVERRIDE 

CERTAIN SELF-DIAGNOSTICS WILL UNDOUBTEDLY BE REQUIRED; THE 
CONSEQUENCE OF THIS DIAGNOSIS AND THE ABILITY TO OVERRIDE 
AND/OR REPROGRAM An AUTOMATED SYSTEM MAY NEED TO BE TRADED 
OFF AGAINST THE DEGREE OF SbPHlSlTlcATIdN NECESSARY FOR "TOTAL' 
AUTONOMY. 



SPECIFIC OBJECTIVES 



CX5 
00 



DISTRIBUTED VERSUS CENTRAL CONTROL 

• IDENTIFY OPTIMUM APPROACH FOR VARIOUS CLASSES OF USE 

(PLANETARY, EARTH ORBITAL, LARGE VS. SMALL, MILITARY) 

• IDENTIFYCOSTVS. BENEFIT OF OPTIMUM APPROACH VS. STANDARD 

• ESTABLISH LEVELS OF AUTHORITY REQUIRED IN EACH 



00 

-p:> 



SPECIFIC OBJECTIVES 



ALGORITHM MODELING 

• GENERATE ALGORITHMS 

• CREATE STANDARD SET OF ALGORITHMS 

• ESTABLISH COST/BENEFIT FOR USE OF STANDARD VS. OPTIMUM 



SPECIFIC OBJECTIVES 



ALGORITHM MODELING 



IDENTIFIED ALGORITHMS 

• BATTERY CHARGE CONTROL 

• BATTERY STATE-OF-HEALTH 

• RECONDITIONING 

• TREND PROJECTION 

• SOLAR ARRAY STATUS 

• COMMAND PROCESSING 

CIRCUIT BREAKER PROGRAMMING 



• SWITCH/LOAD BUS MONITORING 

• FAULT DEFINITION 

• ENERGY PLANNING/ALLOCATION 

• SOLAR ARRAY POWER REALLOCATION 

• LOAD BUS ASSIGNMENTS 

• POWER SUBSYSTEMS STATE-OF-HEALTH 

• REPLACEMENT SCHEDULI^'G 

• CONTROLLER ANOMALIES 



ALGORITHM TYPES 

• EFFECTS ACTION 

• GATHERS DATA 



00 



CO 



SPECIFIC OBJECTIVES 



CONTROL REQUIREMENTS 

• ESTABLISH RATES REQUIRED FOR OPTIMUM MANAGEMENT 

• GENERATION 
•STORAGE 

• DISTRIBUTION 

• DETERMINE SENSITIVITY OF CHANGE IN SAMPLE RATE TO SYSTEM PERFORMANCE, 
RELIABILITY, AND COST 

• ESTABLISH LIMITS OF DATA ALGOFilTHMS DETERMINATION FOR ACTION AND CONSEQUENCES 
OF VARIATIONS IN THOSE LIMITS 



SPECIFIC OBJECTIVES 

CONTROL PHILOSOPHY 

• DETERMINE COST EFFECTIVE LEVELS OF REDUNDANCY {SYSTEM PAD) 

• ESTABLISH LEVELSOF SYSTEM DEGRADATION WHERE SPACECRAFT HIERARCHY DECIDE 
WHETHER TO CONTINUE IN DEGRADED MODE FOR MAXIMUM LIFE OR TO OPERATE IN AN 
EARLY WEAROUT MODE TO ATTAIN HIGHER LEVELS OF PERFORMANCE 

• ESTABLISH MODES OF POWER DOWN OPERATION COMMANDED BY THE SPACECRAFT 
HIERARCHY DUE TO POINTING CONDITIONS, THERMAL CONDITIONS, OR OTHER SPACECRAFT 
CONSTRAINTS. 



00 



SPACE POWER SYSTEM AUTOMATION WORKSHOP 
MARSHALL SPACE FLIGHT CENTER 
OCTOBER 28 & 29, 1981 

REPORT OF WORKSHOP GROUP NUMBER 1 

by 

Sidney W. Silverman (Workshop Chairman) 

Matt Immamura 

Bill Brannian 

Dave Peterson 

Bob Giudici 

Roy Lanier 

John Armantrout 

Doug Turner 



THE QUESTION ADDRESSED 
WAS 
WHAT ARE THE TECHNOLOGY ISSUES INVOLVED IN 
THE AUTOMATION OF A SPACE POWER SYSTEM? 



189 



BACKGROUND ! 

The most iignif leant factor In deriving the technology Issues 

is to define what the word "issues" encompssses, A composite of 
the group's discussion is the following* 

Technology issues aire technical proTxLems/quBstions that wust be 
resolved prior to implementation in a spacecraft or mission in 
order to minimize risk criteria. The issue must meet a defined 
objective. 

In order to be considered an issue, at least one of the follow- 
ing must be truet 

• It has little or no history of use, 

• It requires longer tjian 'normal* project time allowed 
for development, 

kit has unacceptable risk (technical, cost, schedule) 
and value, compared to alternatives. 
In addition— a meaningful RPP can be written for the issue. 



CONGLUSIONS/RECOMMEITOATIONS t 

In order of technical criticality the technical issues arej 

1» To implement the automation and autonomous operation 
of the electrical power system, the prima iry item is the control 
aspect , which implies the software and the verification of the 
sensing and corrective action. This includes sensors to detect 
the selected parameters, algorithms for the component reaction* 
and the subsystem operation and interaction with other components 
and subsystems, and effectors to cover the required ranges of 
values ( for 5O-50OKW spacecraft power systems). The control 
tpi^hnique must assure that the automation of the electrical 
power system is fault-tolerant and can operate in ixrogrammed 
modes iwgardless of the degraded conditions encountered. Control 
concepts thus are the governing factors in effective automation 
and autonomous operation of the electrical power system, 

2. Once the control concept has been selected and the design 
initiated, the next important iter is the availability of srace- 
Qualified components for hiJth nower applications. Included will 
be those components which are available with a past use history. 



190 



those which are logical candidates but have not been qualified, 
those which will have to be modified from existing designs, and 
those which are unavailable for various reasons. The latter will 
result in extensive R40 programs to conceive, fabricate, develop, 
and test the component within the allotted sbfaMiiile. Obmponents 
will have to be suitable for application to a controlled,, auton- 
omous, operational electrical power system. 

3, As the power levels are Increased to the multihundred kilo- 
watt range, higher operating and distributing voltages become nec- 
essary in order to decrease system amperes, losses, and the size of 
the oomponents and the distftbutlon system. Limitations may be 
imposed by^ availability of qualified components. The voltage 
selection will have to be made at the electrical system level 
because of the Interfaces with the other systems and the require- 
Mntft for protectidn and safety* A* higher puwer level* a»d high- 
er voltages or currents, interactions with the environment become 
severe and significant. Special concepts must be formulated so 
that the electrical power system can operate. 



GEfTEEAL i 

A definition of technology readiness can be described in t^ 
following program schedule chart. At the time of technology read- 
iness, all development work will have been completed and only 

design engineering will remain to be done. 

Technology., Technology Ready 



Ready '■ 



R&D, Early Develop- 



^ 



Launch 



For Program 




3-5 Years 



CDR 
Phases G&D 



mm 



191 



SPACE POWER SYSTEM AUTOMATION WORKSHOP 

MARSHALL SPACE FLIGHT CENTER 

OCTOBER 28 & 29, 1981 



REPORT OF WORKSHOP GROUP NUMBER 2 
by 



NAME 

Floyd E. Ford (Chairman) 

Frederick C. Vote 

John W.' Lear 

Charles Sollo 

Joe Navarro 

Mike Glass 

Wayne Hudson 

Don Routh 

Don Williams 



ORGANIZATION 

NASA/GSFC 

JPL 

Martin/Marietta 

TRW 

McDonnell-Douglas V- CA 

Lockheed 

NASA Headquarters 

NASA/MSFC 

NASA/MSFC 



THE QUESTION ADDRESSED 

WAS 

WHAT ARE THE TECHNOLOGY ISSUES INVOLVED IN 
THE AUTOMATION OF A SPACE POWER SYSTEM? 



193 



Background ; 

The group 2 session on Technology Issues (TI) for Automated Power Systems 
was initiated by addressing the following questions: 

• Is the automation of power systems needed or required for future 
space missions requiring large (greater than 25KW) power systems? 

• Is it conceivable to think in terms of an autonomous power system, 
supporting mission objectives for extended periods (several days to weeks) 
without human intervention or monitoring? 

After considerable discussions on such topics as trends in power levels, 
complexity of large systems, user requirements for quality power, overall 
system cost, etc., the group achieved the following consensus: 

a. Automation is required for large power systems. 

b. An autonomous power system is conceivable. 

The group could not agree on the level (or degree) of automation without 
a cost benefit analysis to illustrate the various trade-offs. There was 
general agreement that a fully automated power system would most likely 
be achieved through evolution with incremental growth from today's systems 
to those needed in the 1990' s. However, the technology for automation is 
believed to be one that enables large power systems, not merely to enhanc? 
them. There seems to be no question that the large systems of the future 
will require a much higher degree of automation than that existing in 
present power systems. 

Some other important considerations supporting automation technology for 
power systems are as follows: 

• Large power systems will be extremely complex in terms of on-orbit 
configuration management, amount of housekeeping data, and overall energy 
management. 

• Power and load management will require on-board intelligence to 
efficiently and effectively use the system's energy 

• Speed of detection and correction of failures/faults will be 
critical for large systems. 

• The need for longer periods of spacecraft autonomy is a driver 
for automation. 

The group expressed a need for a trade-off study to establish the 
benefits of automation versus the degree of automation that may be 
achieved in a power system. To place this question in perspective, one 
example is given. Should a power system be completely self-correcting or 
should it depend on ground intervention. For instance, if a failure is 
detected in one of several of the power buses, is it acceptable to the 
users to power down and wait for ground intervention or is there sufficient 
cost justification to automate the diagnostic functions necessary to make 
decisions required to reconfigure the loads to another bus. 



194 



Conclusions /Recommendations : 

The group 2 session defined five technology issues. They are as follows: 

1. Establish a reference power system design from which to base the 
requirements for automation. 

Comment 

The reference system should serve as a baseline for trade-off studies, 
total subsystem analysis, and mission analysis. The reference design 
should consider the environment and user community for low earth orbit, 
geosynchronous, and planetary type missions. The needs of the various 
type pay loads (high power pulse loads, long duty cycle loads, etc.) 
should be a strong consideration in arriving at a reference design. 

2. Develop and document the architecture/methodology to be pursued 
in the automation of large power systems. 

Comment 

The group recognized that any power system consists of a multiplicity of 
basic components such as batteries, solar arrays and electronics. However 
the philosophy used in assembling these components into a *system will 
strongly influence the approach to automation. Such issues as central 
vs. distributed control, type of sensor information needed, processor 
characteristics and storage capability, distribution of intelligence 
within the system (central computer vs. local microprocessors), degree of 
modularization of power units, and the overall system philosophy should 
be thoroughly investigated prior to initiating any hardware development. 
The early decisions made on these issues will impact development cost 
throughout the program. The minimum level of automation consistent with 
a reliable and cost effective power system should be the "first cut" 
design. 

3. Strongly emphasize "system engineering" in the power system 
automation effort. 

Comment 

The successful outcome of an automated power system technology program 
will, to a large extent, depend on the amount of system engineering that 
goes into the decision making process. It must be recognized that the 
power system is only one of the several subsystems that will make up a 
spacecraft, vehicle or space platform. Trade-offs and/or decisions made 
by the power system designer can significantly influence design philosophy 
and/or cost of other subsystems such as mechanical, thermal, data handling, 
attitude control, communication, etc. 

4. Develop models of power systems and system components required 
to generate the algorit:hms that accurately represent the characteristics 
of the individual system components. 



195 



Comment 



The process of automation requires algorithms that accurately represent 
the characteristics of the individual system components. This requires 
that components such as batteries, solar arrays, electronic switches, 
etc., be defined in analytical terms from models that have a high degree 
of validity and accuracy. Both dc and ac models should be developed. 
Performance validation of large power systems will depend primarily on 
synthesizing the system using computer simulations. This is contrasted 
with past practices where "all up" ground system tests were conducted to 
demonstrate system performance prior to launch. 

5. Identify and initiate development of components required for the 
automation of power systems. 

C omments 

It was generally agreed that the basic piece parts (battery cells, solar 
cells, transistors, etc.) for a power system currently exist. However, a 
number of components required for the automation process either do not 
exist, or are inadequate. Those specifically discussed included high 
power overload switches (space qualified), actuators with digital 
interface, electronic switchgear (non-mechanical) and accurate current 
sensors with large dynamic range. 



196 



General: 

The overall view of the group, as perceived by the chairman, was that 
large space power systems will require levels of automation much greater 
than those being implemented in present designs. The architecture of the 
large power system, the philosophy of design, the methodology of hardware 
implementation, and the launch and operational scenarios are presently 
nonexistent. These are interdependent quantities and are usually studied 
and defined as part of a project conceptual design phase. Consequently, 
it is understandable that most of the issues addressed during the workshop 
dealt with system engineering rather than technology. Of the five recommen- 
dations presented by group 2, only numbers 4 and 5 relate to technology. 
What is implied by this, is that a technology program for the automation 
of power systems must emphasize systems engineering first . From the 
systems engineering a number of technology issues will emerge. 

During the workshop discussions, it became apparent that there are two 
prevailing "schools of thought" on large power systems in space. They 
are as follows: 

• Develop power system modules (i.e., 25KW) and use these moaules 
as building blocks in space for growth to a 100 to 250KW capability over 
some period. 

• Develop a "unit" power system of the size that is needed (i.e., 
100 or 200KW) and place this unit in orbit. 

The second approach has been referred to as a "mini-utility" system. The 
point of raising this issue is not to promote one concept over the other, 
but rather to illustrate the divergence of technical opinions, even on 
the basic scenario "for achieving large power capabilities in space. 



197 



SPACE POWER SYSTEM AUTOMATION WORKSHOP 
MARSHALL SPACE FLIGHT CENTER 
OCTOBER 28 & 29, 1981 

REPORT OF WORKSHOP GROUP NUMBER 3 

by 

Howard Weiner (Workshop Chairman) 

Robert Corbet t 

Kent Decker 

Joe Voss 

Lu Slifer 

Chris Carl 

George Von Tiesenhausen 

Lt. Ed Gjermundsen 



THE QUESTION ADDRESSED 
WAS 
WHAT ARE THE SPECIFIC OBJECTIVES INVOLVED IN 
THE AUTOMATION OF A SPACE POWER SYSTEM? 



199 



BACKGROUND 

Workshop Group No. 3 was assigned the task of establishing 
specific objectives involved in the automation of a space power 
subsystem. Considerable attention was also given to the "strawman" 
set of objectives developed by NASA-MSFC personnel. As a result 
of these discussions a set of recommendations, presented below, 
were derived. These recommendations do not necessarily represent 
all of the objectives required for automation. However, they do 
represent a well-conisdered set of initial specific objectives. 

RECOMMENDATIONS 

This section contains a set of recommendations arranged in 
order of decreasing priority (i.e. Recommendation No. 1 has highest 
priority) . Each recommendation is also a brief description of the 
action needed to accomplish a specific objective. 

Priority ranking was based on a temporal ranking. Thus, the 
specific objective of Recommendation No. 2 needed substantial 
completion before specific objectives of subsequent recommendations 
could be meaningfully attained. 

RECOMMENDATION NO. 1 

Identify All Potentially Useful Autonomy Functions 

An Autonomy Function is defined herein as a specific 
capability, designed into a spacecraft which permits the spacecraft 
to execute a specific on-board task (with decision making) without 
intervention or control from the ground. 

A number of autonomy functions have been identified, which 
are useful for power subsystem autonomy, including: 

1) Battery Charge Control 

2) Battery State-of-Health 

Reconditioning 
Trend Projection 

3) Solar Array Status 

4) Command Processing (Circuit Breaker Programming) 

5) Switch/Load Bus Monitoring (Fault Definition) 

6) Energy Planning/Allocation (Solar Array Power 

Relocation) 

7) Load Bus Assignments 

8) Power Subsystems State-of-Health 

Replacement Schedules 
Controller Anomalies 



200 



While these functions may appear to be sufficient, there 
can be more subtle considerations, based on a more global viewpoint 
than that of a power subsysTefiPdetigner , which require additional 
autonomy functions be utilized for the larger more complex space- 
craft. A proper understanding of these considerations can be 
attained by the use of a team of experts from the following space- 
craft technologies : 

1) Artificial Intelligence 

2) Spacecraft Systems 

3) Power Subsystems 

4) Computer Design/Programming 

Thest teams should be capable of identifying, categorizing 
and prioritizing all potentially useful autonomy functions. As an 
example, it may be useful to utilize the following categories as 
autonomy function discriminators . 

1) Level of Control Authority 

- System 
Subsystem 

- Local 

2) Response Time Requirement 

- Fast (%10-D Sec) 

- Moderate ('vlO-3 Sec) 

- Slow (^1 Sec) 

3) Mission Impact 

Critical 
Non-Critical 

By means of these categories, etc, the optimiom methods of implementing 
an autonomy function can be more easily attained. 

RECOMMENDATION NO. 2 

Establish Design and Reliability Directives for the Power 
Subsystem 

Another key task for the team of experts is the establish- 
ment of Design and Reliability Directives for the Power Subsystem. 
This task should be at as high a priority level as the first task 
of identifying all potentially useful autonomy functions. 

The team should carefully review all mission and operations 
requirements in order to determine the appropriate levels of per- 
formance, reliability and autonomy for the power subsystem. Directives 
should then be issued for controlling design. As an example: 

"Failure of an autonomy function shall not cause any 
degradation of power subsystem performance or lifetime" 

Directives, such as the above, can then be used to determine 
levels of redundancy in autonomy function and power subsystem equip- 
ment as well as the type of redundancy (block, functional, standby, 
etc) . 

201 



These directives will also serve as the basis for 
determining optimtam monitoring approach, data sample rates and 
other elements of the autonomy functions. 

RECOMMENDATION NO. 3 

Generate Algorithms for Each Autonomy Function 

An Algorithm is defined herein as a series of logical 
steps needed to perform an A utonomy Function . 

In order to determine the optimum level of autonomy for 
a given power subsystem, the penalties vs benefits of various 
applicable autonomy function must be evaluated. Assessment of 
these require that an algorithm, for each function, be generated 
and that various methods of implementing that algorithm hardware, 
software, memory, data rate, sensors, data conversion, etc be 
evaluated. Hence, prior to the selection of any autonomy functions, 
tor a given application, it is desirable that algorithms be generated 
for all potentially useful autonomy functions. 

It should be noted that development of standard algorithms 
may be useful in terms of generating penalty information during the 
preliminary design process. However, algorithms and methods of 
implementing these algorithms should be optimized by the time the 
critical design review process occurs. 

RECOMMENDATION NO. 4 

Develop a More Rigorous Definition of Potential C omputer 
Arrangements ~ ~~ ~ 

As development of spacecraft autonomy proceeds, it will 
become necessary to develop more rigorous definitions of proposed 
computer arrangements. The present scheme of "Distributed", "Hybrid" 
or "Central Control" arrangements can lead to confusion during 
evaluation and trade-off processes. A proposed approach (which 
should be modified as more complex arrangements are developed) is 
shown in Figure 1. The approach is simply to indicate the numbers 
of computers at successively lower levels of command and control 
heirarchy. The arrangements shown in Figure 1 are based on the 
following heirarchy: 

1) Spacecraft System Level 

2) Subsystem Level 

3) Local Level 

Additional definitions of arrangements should be developed 
when computers are used on a ring (or circular) type of data bus. 



202 



RECOMMENDATION NO . 5 

identify Opt imxjm Computer Arrangements Based on the Size 
of the Size of the SpacecraTt 

The "size" of a spacecraft, in terms pertinent to power 
system autonomy, may be the physical size of the spacecraft or the 
power subsystem, the power requirements of the spacecraft, the degree 
of "complexity" of the power subsystem or the rate of command, control 
and monitoring data - or any combination of the above. Essentially, 
the "larger" the spacecraft, the more likely a "distributed" computer 
arrangement will be required. As an example, if the data rate 
required for power subsystem autonomy is of the order of 'VilOO KHZ, 
the use of the spacecraft central computer alone may be sufficient, 
On the other hand, a data rate of lOMHZ will require distribution 
of autonomy tasks between a spacecraft central computer ('v3MHZ presently 
available) , a power subsystem computer (-vSMHZ) and numerous of local 
level processors (lOOKHZ - 800 KHZ). 

Other considerations such as a planetary vs earth orbital 
spacecraft, a military vs civil spacecraft or levels of authority 
for each processor are relatively minor with regard to their impact 
on computer arrangements. 

A standard computer arrangement for all spacecraft "sizes" 
is not indicated. Nor is it even indicated for all classes of space- 
craft for a given ''size". In the final analyses, an optimum computer 
arrangement will be used in the final design of autonomy for any ^^ 
power subsystem, even though a majority of the developed "standard 
autonomous functions will find multiple application. 



203 



SPACE POWER SYSTEM AUTOMATION WORKSHOP 
MARSHALL SPACE FLIGHT CENTER 
OCTOBER 28 & 29, 1981 

REPORT OF WORKSHOP GROUP NUMBER 4 

by 

Wayne Wagnon (Workshop Chairman) 

Ron Larson 

Fred Lukens 

Art Schoenfeld 

Ron Given 

Irving Stein 

C. S. Crowell 

Dave Massie 

Dick Gualdoni 



THE QUESTION ADDRESSED 
WAS 
WHAT ARE THE SPECIFIC OBJECTIVES INVOLVED IN 
THE AUTOMATION OF A SPACE POWER SYSTEM? 



205 



SPACE POWER SYSTEM 

AUTOMATION WORKSHOP 

INPUT FROM 

GROUP 4 

This document summarizes the inputs by the individual members 
comprising Group 4 on Automation Objectives. 

Background ; 

With the current emphasis being placed on space platform systems, 
it becomes necessary to investigate new way's to make these 
systems affordable. That is, affordable in terras of reducing the 
life cycle costs, extend the operational life, and improve the 
performance of the systems involved. To this end, automation and 
autonomous systems technologies are expected to make significant 
and important contributions to the development and operation of these 
missions. 

In the case of the on-board electrical power system, a program must 
be defined and implemented that is affordable and will ensure, in 
the event of a failure, that the system degrades gracefully while 
providing for some minimum set of useful services. Thesrefore, the 
most basic of al-1 objectives is to define an electrical power system 
automation plan that will achieve the greatest ear ly-on benefits 
(such as timely reconfiguration and reconstitution of itself) without 
adding to the complexity of a fully autonomous system. 

Conclusions ; 

Much has been accomplished in providing new automation tools to 
the hardware designer that improves the performance of today's 
flight equipment. Microprocessors are being used to program and 
control system level functions with excellent results. In the cast 
of space power systems, many of the technology issues involving dis- 
tributed versus central control, algorithm modeling, control reguire'- 
ments/philosophy, voltage type/level, partitioning between spacecraft 
and ground and between hardware and man, etc. can be resolved through 
the application of automation techniques. To be successful , automa- 
tion must be implemented as an integral part of the system design 
to ensure that the power demands of the users are met with the 
greatest reliability, flexibility and efficiency. 

Recommendations : 

The objectives and actions taken to evaluate -and implement an agreed 
upon level and/or philosophy of automation for a space power subsystem 



206 



must be focused so as to provide a utility type of operation. 
It must also reduce the groxond and on-board operational burden, 
accommodate near-term hardware technology limitations and reduce 
the development, operations, and resupply costs of the system. 
Based upon this premise, the following recommendat.ions are made: 

1. Classify and characterize the power subsystem require- 
ments. This includes the function, quality, type, voltage level, 
quantity, constraints, load profiles, etc. In addition, this 
action should consider all potential power utilization equipments 
as well as the mission phases (i.e., pre-launch, launch, orbital 
operations, on -orbit service/maintenance/resupply, etc.). 

2. Develop, a comprehensive list of all potential functions 
and/or activities that could impact the power siabsystem and pre- 
vent it from performing an effective utility type of operation. 
This would include such parameters as operational environments, 
single point failures, insufficient redundancy, unqualified parts 
and components, human error, over-stressed conditions, poor design 
concepts, inadequate protection, inaccurate sensors, etc. 

3. Generate a candidate list of automation activities that 
would eliminate and/or minimize all the identified impacts and 
would provide both a short term and long term benefit to the power 
subsystem if implemented. Items to be considered would include 
redundancy, component derating, fault management, shifting of burden 
from man to machines, application of algorithms for management 
strategies, partitioning of functions between space platform and 
ground and between man and machines, application of hiearchy control 
functions, level of monitoring, etc. 

4. Conduct an indepth trade-off study to evaluate and analyze 
those candidate automation activities selected as having the 
maximum pay-off or benefits for the space power system. Questions 
to be addressed would include the type sensors to be used, level of 
redundancy to employ, derating factors, central vs distributed 
control, control strategies, sampling rates, fault detection 
methodologies;, response times, operational limits,, diagnosis routines, 
etc. 

5. Develop a balanced partitioning of the automation and control 
functions between the ground, the space platform and the power sub- 
system. The partioning should be based on such factors as selected 
control sensors, sensor control circuitry, integration methodology, 
applicable control algorithms, display requirements, redline para- 
meters, telemetry links, communication bandwidths, data pre-processing, 
etc. 

6. Develop a fault detection, isolation, diagnosis, and pro- 
tection plan. The plan should consider such parameters as interface 
requirements, equipment reconfiguration and recovery requirements. 



207 



"safing" for on-orbit servicing, supervisory controls for load 
switching, system protection for out-of -tolerance conditions, 
load limiters, reconditioning, trend analysis, etc. 

7. Develop algorithms, as appropriate, for the following 

functions: 

a) Battery management strategies 

b) Bus power allocations 

c) Power distribution management 

d) Power processing management 

e) Thermal mamagement 

f) Battery reconditioning 

g) Monitoring health status 
h) Trend analysis 

i) Fault recovery/reconfiguration 

j ) Platform processor interfacing 

k) Platform display and man interfacing 

1) Ground support interfacing 

m) Sensing/control parameters 

n) Test and validation 

These algorithms are intended to enhance and to enable the imple- 
mentation of selected automation activities to improve performance, 
reduce costs, and to extend the useful life of the space power sub- 
system. 

8. Develop a technology readiness demonstration program to 
validate and assess the automation functions and methodology 
employed. In addition to exercising and validating the specific 
automation efforts incorporated into the design and those imposed 
on the power subsystem, the demonstration will include a complete 
dynamic performance and stability characteristics of the system. 
Individual parameters such as the following are to be included: 



208 



a) Load switching 

b) Reconfiguration 

c) Fault recovery 

d) Fault isolation 

e) Power regulation 

f) Power processing 

g) Sensor response 

h) Circuit protection 

i ) Other 

9. Define, develop and verify the needed automation tech- 
nology for items such as* the following: 

a) Sensors 

b) Sensor circuits 

c) Soli"d state circuit breakers 

d) Fault isolation switches 

e) Load limiters 

f) Data processors 

The above nine areas of activity are in priority in that they are 
listed in the normal sequence of events to accomplish the broad 
automation objectives previously stated. A carefully planned and 
coordinated implementation automation plan will have significant 
benefits making a space platform system affordable. 



209 



NAME 

Jim Miller 
(205-453-4950) 



Dick Carlisle 
(202-755-2403) 



Chris Carl 
(792-2018 FTS) 



Sidney W. Silverman 
(206-773-2457) 



Joseph M. Voss 
(206-773-1198) 



Frederick C. Vote 
(213-354-4182) 



Fred Lukens 
(303-798-8752) 



Robert E. Corbett 
(408-742-3305^ 



Floyd E. Ford 
(301-344-5845) 



Lu Slifer 
(301-344-5845) 



SPACE POWER SYSTEM 
AUTOMATION WORKSHOP 
AT THE 
MARSHALL SPACE FLIGHT CENTER 
OCTOBER 27-29, 1981 

ATTENDEES 

ADDRESS 

Marshall Space Flight Center 

ECU 

Marshall Space Flight Center, AL 35812 

RSS-5 

National Aeronautics & Space Administration 

600 Independence Blvd. 

Washington, D.C. 20546 

Jet Propulsion Lab 

233-307 

4800 Oak Grove Dr. 

Pasadena, CA 91030 

Boeing Aerospace Co . 
(Prefer home address for mailing) 
19630 Marine View Drive, S.W. 
Seattle, Wash. 98166 

Boeing Aerospace Co. 
Org. 2-3743, M/S 8C-62 
P.O.B. 3999 
Seattle, WA 98124 

Jet Propulsion Lab 
Mail Stop 198-220 
4800 Oak Grove Drive 
Pasadena, CA 91109 

Martin Marietta 
Mail Stop S0550 
P.O.Box 179 
Denver. CO 80201 

Lockheed Missiles & Space Co. 
D/62-16 B/151 
P.O. Box 504 
Sunnyvale, CA 94086 

NASA/Goddard Space Flight Center 
Code 711 
Breenbelt, MD 21077 

NASA/Goddard Space Flight Center 
Code 711 
Greenbelt, MD 21077 



211 



ATTENDEES 



NAME 

Howard Weiner 
(213-648-6273) 



Wayne Wagnon 
(205-453-4623) 



George von Tiesenhausen 
(2054453-2789) 



Charles Sollo 
(213-535-1712) 



Arthur D, Schoenfeld 
(213-536-1972) 



William R. Brannian 
(213-536-1971) 



Jerome P. Mullin 
(202-755-3278) 



Jim Graves 
(205-453-2514) 



Kent Decker 
(213-536-2960) 



Douglas Turner 
(213-354-2346) 



Joe Navarra 
(714-896-4551) 



Dave Massie 
(513-255-6235) 



ADDRESS 

The Aerospace Corp. 
Mail Station: D8-1102 
P. 0. Box 92957 
Los Angeles, CA 90009 

Marshall Space Flight Center 

Code EC31 

Marshall Space Flight Center, AL 35812 

Marshall Space Flight Center 

PSOl 

Marshall Space Flight Center, AL 35812 

TRW, M2-2120 

One Space Park 

Redondo Beach, CA 90278 

TRW, M2-2020 

One Space Park 

Redondo Be^ch, CA 90278 

TRW/STG, M2/2020 

One Space Park 

Redondo Beach, CA 90278 

National Aeronautics and Space Administration 

RTS-6 

600 Independence Blvd. 

Washington, D.C. 20546 

Marshall Space Flight Center 

EC12 

Marshall Space Flight Center, AL 35812 

TRW 

M2-2384 

One Space Park 

Redondo Beach, CA 90278 

jet Propulsion Lab. 
4800 Oak Grove Dr. 
Pasadena, CA 91030 

McDonnell Douglas Astronautics Co. 
5301 Balsa Ave. 
Huntington Beach, CA 92647 

A. F. Aero Propulsion Lab 

AFAP/POE 

Wright Patterson AFB 

Dayton, OH 45433 



212 



ATTENDEES 



NAME 



Lt. Ed Gjermtindsen 
^(213-615-4195) 



Jack MacPherson 
(205-453-1023) 



Mike Glass 



Ron Given 
(408-742-5194) 



Jon Armantrout 
(408-743-2614) 



Larry Chidester 
(408-742-2270) 



Roy Lanier, Jr, 
(205-453-2113) 



Paul Crawford 
(714-896-4858) 



Wayne Marcus 
(714-896-4309) 



Donald E. Williams 
(205-453-3666) 



Harry Buchanan 
(205-453-4582) 



C. S. Crowell 
(205-453-4637) 



John W. Lear 
(303-977-5457) 



ADDRESS 

Headquarters -Space Division (AFSD) 

YLXT 

Los Angeles Air Force Station 

P. 0. Box 92960 

Los Angeles, CA 90009 

Marshall Space Flight Center 

EROl 

Marshall Space Flight Center, AL 35812 

Lockheed Missiles & Space Co. 
P. 0. Box 504 B/151 0/6216 
Sunnyvale, CA 94086 

Lockheed Missiles & Space Co. 
P. 0. Box 504 B/151 0/6216 
Sunnyvale, CA 94086 

Lockheed Missiles & Space Co. 
P. 0. Box 504 B/151 0/6216 
Sunnyvale, CA 94086 

Lockheed Missiles & Space Co. 
P. 0. Box 504 B/151 0/6216 
Sunnyvale, CA 94086 

Marshall Space Flight Center 

EC12 

Marshall Space Flight Center, AL 35812 

McDonnell Douglas 

5301 Bolsa Ave. M/S14-3 

Huntington Beach, CA 92647 

McDonnell Douglas 

5301 Bolsa Ave, M/S14-3 

Huntington Beach, CA 92647 

Marshall Space Flight Center 

PD14 

Marshall Space Flight Center, AL 35812 

Marshall Space Flight Center 

ED15 

Marshall Space Flight Center, AL 35812 

Marshall Space Flight Center 

EC13 

Marshall Space Fliglit Center, AL 35812 

Martin Marietta Denver Aerospace 

MS 1130 

P. O.Box 179 

Denver, CO 80201 



213 



ATTENDEES 



NAME 

Irv Stein 
(213-354-6048) 
FTS 792-6048 



Dave Peterson 
(714-277-8900) 
ext 2204 



Wayne Hudson 
(202-755-3278) 



Richard A. Gualdoni 
(202-755-2403) 



Ronald L. Lars en 
(202-755-3273) 



Matt S. Imamura 
(303-977-0701) 



Don Routh 
(205-453-3773) 



Danny Xenofos 
(205-453-4261) 



ADDRESS 

Jet Propulsion Lab 
M.S. 198-224 
4800 O^k Grove Dr. 
Pasadena, CA 91109 

General Dynamics -Convair 
M.S. 41-6760 
P. 0. Box 80847 
San Diego, CA 92138 

National Aeronautics and Space Administration 

RTS-6 

600 Independence Blvd. 

Washington, D.C. 20546 

National Aeronautics & Space Administration 

RSS-5 

600 Independence Blvd. 

Washington, D.C. 20546 

National Aeronautics & Space Administration 

RTE-6 

600 Independence Blvd. 

Washington, D.C. 20546 

Martin Marietta Corp. 
P. 0, Box 179 
Denver, CO 80201 



Marshall Space Flight Center 

PD14 

Marshall Space Flight Center, AL 35812 

NASA/Marshall Space Flight Center 

PD24 

Marshall Space Flight Center, AL 35812 



214 



1. REPORT NO. 

NASA CP-2213 



2. GOVERNMENT ACCESSION NO. 



4. TITLE AND SUBTITLE 

Space Power Subsystem Automation Technology 



7. AUTHOR(S) 

Compiled by Jame s R. Graves 



9. PERFORMING ORGANIZATION NAME AND ADDRESS 

George C. Marshall Space Flight Center 
Marshall Space Flight Center, Alabama 35812 



12. SPONSORING AGENCY NAME AND ADDRESS 



National Aeronautics and Space Administration 
Washington, DC 20546 



3. RECIPIENT'S CATALOG NO. 



5. REPORT DATE 

March 1982 



6. PERFORMtNG ORGANIZATION CODE 



8. PERFORMING ORGANIZATION REPORT # 



10. WORK UNIT NO. 
M-371 



11. CONTRACT OR GRANT NO. 



13. TYPE OF REPORT 8e PERIOD COVERED 

Conference Publication 



l-l. SPONSORING AGENCY CODE 



15. SUPPLEMENTARY NOTES 

Proceedings of a Conference/Workshop held at the Marshall Space Flight Center, 
Alabama, October 28-29, 1981. 



16. ABSTRACT 

With the rapidly increasing interest in the application of automation techniques to space 
power subsystems, the Office of Aeronautics and Space Technology decided to hold a workshop 
during the last week of October 1981. About 50 specialists convened at the Marshall Center 
for the two-day interchange. The technology issues involved in power subsystem automation 
and the reasonable objectives to be sought in such a program were discussed. After a full day 
of review of current programs, progress, and plans, the participants were divided into four 
workshops to discuss the different aspects of these issues and objectives. ' These proceedings 
gave insight into the complexities, uncertainties, and alternatives of power subsystem auto- 
mation, along with the advantages from both an economic and a technological perspective. 
Whereas most spacecraft power subsystems now use certain automated functions, the idea of 
complete autonomy for long periods of time is almost inconceivable. Thus, it seems prudent 
that the technology program for power subsystem automation be based upon a growth scenario 
which should provide a structured framework of deliberate steps to enable the evolution of 
space power subsystems from the current practice of limited autonomy to a greater use of auto 
mation with each step being justified on a cost/benefit basis. Each accomplishment should move 
toward the objectives of decreased requirement for ground control, increased system reliabi- 
lity through on-board management, and ultimately lower energy cost through longer life sys- 
tems that require fewer resources to operate and maintain. This approach seems well-suited 
to the evolution of more sophisticated algorithms and eventually perhaps even the use of some 
sort of artificial intelligence. On thing seems certain: Multi-hundred kilowatt systems of the 
future will require an advanced level of autonomy if they are to be affordable and manageable. 

DISTRIBUTION STATEMENT 



17. KEY WORDS 



Spacecraft automation technology 
Automation components technology 
Power system autonomy 



19. SECURITY CLASSIF. (of thU reports 

Unclassified 



18. 



Unclassified - Unlimited 



Subject Category 20 



20. SECURITY CLASSIF. (of thU page) 

Unclassified 



21. NO. OF PAGES 

215 



22. PRICE 
AlO 



For sale by National Technical Infoimation Service, Springfield. Virginia 22161 

NASA-Langley, 1982 



National Aeronautics and 
Space Administration 

Washington, D.C. 
20546 

Official Business 

Penalty for Private Use, $300 



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